diff --git a/resources/lang/en.json b/resources/lang/en.json
index 64c491ee9..701c383fa 100644
--- a/resources/lang/en.json
+++ b/resources/lang/en.json
@@ -400,7 +400,8 @@
     "sams": "SAMs",
     "warships": "Warships",
     "health": "Health",
-    "attitude": "Attitude"
+    "attitude": "Attitude",
+    "levels": "Levels"
   },
   "events_display": {
     "retreating": "retreating",
@@ -411,7 +412,9 @@
     "unit_type_unknown": "Unknown",
     "close": "Close",
     "cooldown": "Cooldown",
-    "type": "Type"
+    "type": "Type",
+    "upgrade": "Upgrade",
+    "level": "Level"
   },
   "relation": {
     "hostile": "Hostile",
diff --git a/src/client/Transport.ts b/src/client/Transport.ts
index e9124b6f5..b1e73fded 100644
--- a/src/client/Transport.ts
+++ b/src/client/Transport.ts
@@ -44,6 +44,13 @@ export class SendBreakAllianceIntentEvent implements GameEvent {
   ) {}
 }
 
+export class SendUpgradeStructureIntentEvent implements GameEvent {
+  constructor(
+    public readonly unitId: number,
+    public readonly unitType: UnitType,
+  ) {}
+}
+
 export class SendAllianceReplyIntentEvent implements GameEvent {
   constructor(
     // The original alliance requestor
@@ -187,6 +194,9 @@ export class Transport {
       this.onSendSpawnIntentEvent(e),
     );
     this.eventBus.on(SendAttackIntentEvent, (e) => this.onSendAttackIntent(e));
+    this.eventBus.on(SendUpgradeStructureIntentEvent, (e) =>
+      this.onSendUpgradeStructureIntent(e),
+    );
     this.eventBus.on(SendBoatAttackIntentEvent, (e) =>
       this.onSendBoatAttackIntent(e),
     );
@@ -427,6 +437,15 @@ export class Transport {
     });
   }
 
+  private onSendUpgradeStructureIntent(event: SendUpgradeStructureIntentEvent) {
+    this.sendIntent({
+      type: "upgrade_structure",
+      unit: event.unitType,
+      clientID: this.lobbyConfig.clientID,
+      unitId: event.unitId,
+    });
+  }
+
   private onSendTargetPlayerIntent(event: SendTargetPlayerIntentEvent) {
     this.sendIntent({
       type: "targetPlayer",
diff --git a/src/client/graphics/layers/PlayerInfoOverlay.ts b/src/client/graphics/layers/PlayerInfoOverlay.ts
index 099a865e2..261fd3f0f 100644
--- a/src/client/graphics/layers/PlayerInfoOverlay.ts
+++ b/src/client/graphics/layers/PlayerInfoOverlay.ts
@@ -240,18 +240,58 @@ export class PlayerInfoOverlay extends LitElement implements Layer {
         <div class="text-sm opacity-80" translate="no">
           ${translateText("player_info_overlay.ports")}:
           ${player.units(UnitType.Port).length}
+          ${player
+            .units(UnitType.Port)
+            .map((unit) => unit.level())
+            .reduce((a, b) => a + b, 0) > 1
+            ? html`(${translateText("player_info_overlay.levels")}:
+              ${player
+                .units(UnitType.Port)
+                .map((unit) => unit.level())
+                .reduce((a, b) => a + b, 0)})`
+            : ""}
         </div>
         <div class="text-sm opacity-80" translate="no">
           ${translateText("player_info_overlay.cities")}:
           ${player.units(UnitType.City).length}
+          ${player
+            .units(UnitType.City)
+            .map((unit) => unit.level())
+            .reduce((a, b) => a + b, 0) > 1
+            ? html`(${translateText("player_info_overlay.levels")}:
+              ${player
+                .units(UnitType.City)
+                .map((unit) => unit.level())
+                .reduce((a, b) => a + b, 0)})`
+            : ""}
         </div>
         <div class="text-sm opacity-80" translate="no">
           ${translateText("player_info_overlay.missile_launchers")}:
           ${player.units(UnitType.MissileSilo).length}
+          ${player
+            .units(UnitType.MissileSilo)
+            .map((unit) => unit.level())
+            .reduce((a, b) => a + b, 0) > 1
+            ? html`(${translateText("player_info_overlay.levels")}:
+              ${player
+                .units(UnitType.MissileSilo)
+                .map((unit) => unit.level())
+                .reduce((a, b) => a + b, 0)})`
+            : ""}
         </div>
         <div class="text-sm opacity-80" translate="no">
           ${translateText("player_info_overlay.sams")}:
           ${player.units(UnitType.SAMLauncher).length}
+          ${player
+            .units(UnitType.SAMLauncher)
+            .map((unit) => unit.level())
+            .reduce((a, b) => a + b, 0) > 1
+            ? html`(${translateText("player_info_overlay.levels")}:
+              ${player
+                .units(UnitType.SAMLauncher)
+                .map((unit) => unit.level())
+                .reduce((a, b) => a + b, 0)})`
+            : ""}
         </div>
         <div class="text-sm opacity-80" translate="no">
           ${translateText("player_info_overlay.warships")}:
diff --git a/src/client/graphics/layers/StructureLayer.ts b/src/client/graphics/layers/StructureLayer.ts
index 180005d26..180e838ab 100644
--- a/src/client/graphics/layers/StructureLayer.ts
+++ b/src/client/graphics/layers/StructureLayer.ts
@@ -242,13 +242,13 @@ export class StructureLayer implements Layer {
     const config = this.unitConfigs[unitType];
     let icon: ImageData | undefined;
 
-    if (unitType === UnitType.SAMLauncher && unit.isCooldown()) {
+    if (unitType === UnitType.SAMLauncher && unit.isInCooldown()) {
       icon = this.unitIcons.get("reloadingSam");
     } else {
       icon = this.unitIcons.get(iconType);
     }
 
-    if (unitType === UnitType.MissileSilo && unit.isCooldown()) {
+    if (unitType === UnitType.MissileSilo && unit.isInCooldown()) {
       icon = this.unitIcons.get("reloadingSilo");
     } else {
       icon = this.unitIcons.get(iconType);
@@ -268,13 +268,13 @@ export class StructureLayer implements Layer {
     if (!unit.isActive()) return;
 
     let borderColor = this.theme.borderColor(unit.owner());
-    if (unitType === UnitType.SAMLauncher && unit.isCooldown()) {
+    if (unitType === UnitType.SAMLauncher && unit.isInCooldown()) {
       borderColor = reloadingColor;
     } else if (unit.type() === UnitType.Construction) {
       borderColor = underConstructionColor;
     }
 
-    if (unitType === UnitType.MissileSilo && unit.isCooldown()) {
+    if (unitType === UnitType.MissileSilo && unit.isInCooldown()) {
       borderColor = reloadingColor;
     } else if (unit.type() === UnitType.Construction) {
       borderColor = underConstructionColor;
@@ -391,6 +391,7 @@ export class StructureLayer implements Layer {
         const screenPos = this.transformHandler.worldToScreenCoordinates(cell);
         const unitTile = clickedUnit.tile();
         this.unitInfoModal?.onOpenStructureModal({
+          eventBus: this.eventBus,
           unit: clickedUnit,
           x: screenPos.x,
           y: screenPos.y,
diff --git a/src/client/graphics/layers/UILayer.ts b/src/client/graphics/layers/UILayer.ts
index 9918d8c4f..c9fa49933 100644
--- a/src/client/graphics/layers/UILayer.ts
+++ b/src/client/graphics/layers/UILayer.ts
@@ -128,7 +128,7 @@ export class UILayer implements Layer {
       }
       case UnitType.SAMLauncher:
       case UnitType.MissileSilo:
-        if (unit.isActive() && unit.isCooldown()) {
+        if (unit.isActive() && unit.isInCooldown()) {
           const endTick = unit.ticksLeftInCooldown() || 0;
           this.drawLoadingBar(unit, endTick);
         }
diff --git a/src/client/graphics/layers/UnitInfoModal.ts b/src/client/graphics/layers/UnitInfoModal.ts
index 0066aa309..cee548768 100644
--- a/src/client/graphics/layers/UnitInfoModal.ts
+++ b/src/client/graphics/layers/UnitInfoModal.ts
@@ -1,8 +1,10 @@
 import { LitElement, css, html } from "lit";
 import { customElement, property } from "lit/decorators.js";
 import { translateText } from "../../../client/Utils";
+import { EventBus } from "../../../core/EventBus";
 import { UnitType } from "../../../core/game/Game";
 import { GameView, UnitView } from "../../../core/game/GameView";
+import { SendUpgradeStructureIntentEvent } from "../../Transport";
 import { Layer } from "./Layer";
 import { StructureLayer } from "./StructureLayer";
 
@@ -15,6 +17,7 @@ export class UnitInfoModal extends LitElement implements Layer {
 
   public game: GameView;
   public structureLayer: StructureLayer | null = null;
+  private eventBus: EventBus;
 
   constructor() {
     super();
@@ -29,12 +32,14 @@ export class UnitInfoModal extends LitElement implements Layer {
   }
 
   public onOpenStructureModal = ({
+    eventBus,
     unit,
     x,
     y,
     tileX,
     tileY,
   }: {
+    eventBus: EventBus;
     unit: UnitView;
     x: number;
     y: number;
@@ -44,6 +49,7 @@ export class UnitInfoModal extends LitElement implements Layer {
     if (!this.game) return;
     this.x = x;
     this.y = y;
+    this.eventBus = eventBus;
     const targetRef = this.game.ref(tileX, tileY);
 
     const allUnitTypes = Object.values(UnitType);
@@ -119,12 +125,44 @@ export class UnitInfoModal extends LitElement implements Layer {
     .close-button:hover {
       background: #a00;
     }
+
+    .upgrade-button {
+      background: #3a0;
+      color: #fff;
+      border: none;
+      border-radius: 4px;
+      font-size: 14px;
+      font-weight: bold;
+      cursor: pointer;
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      line-height: 1;
+      padding: 6px 12px;
+    }
+
+    .upgrade-button:hover {
+      background: #0a0;
+    }
   `;
 
   render() {
     if (!this.unit) return null;
 
-    const cooldown = this.unit.ticksLeftInCooldown() ?? 0;
+    const ticksLeftInCooldown = this.unit.ticksLeftInCooldown();
+    let configTimer;
+    switch (this.unit.type()) {
+      case UnitType.MissileSilo:
+        configTimer = this.game.config().SiloCooldown();
+        break;
+      case UnitType.SAMLauncher:
+        configTimer = this.game.config().SAMCooldown();
+        break;
+    }
+    let cooldown = 0;
+    if (ticksLeftInCooldown !== undefined && configTimer !== undefined) {
+      cooldown = configTimer - (this.game.ticks() - ticksLeftInCooldown);
+    }
     const secondsLeft = Math.ceil(cooldown / 10);
 
     return html`
@@ -140,6 +178,16 @@ export class UnitInfoModal extends LitElement implements Layer {
           <strong>${translateText("unit_info_modal.type")}:</strong>
           ${translateText(+"unit_type." + this.unit.type?.().toLowerCase()) ??
           translateText("unit_info_modal.unit_type_unknown")}
+          <strong
+            style="display: ${this.game.unitInfo(this.unit.type()).upgradable
+              ? "inline"
+              : "none"};"
+            >${translateText("unit_info_modal.level")}:</strong
+          >
+          ${this.game.unitInfo(this.unit.type()).upgradable &&
+          this.unit.level?.()
+            ? this.unit.level?.()
+            : ""}
         </div>
         ${secondsLeft > 0
           ? html`<div style="margin-bottom: 4px;">
@@ -147,7 +195,30 @@ export class UnitInfoModal extends LitElement implements Layer {
               ${secondsLeft}s
             </div>`
           : ""}
-        <div style="margin-top: 14px; display: flex; justify-content: center;">
+        <div
+          style="margin-top: 14px; display: flex; justify-content: space-between;"
+        >
+          <button
+            @click=${() => {
+              if (this.unit) {
+                this.eventBus.emit(
+                  new SendUpgradeStructureIntentEvent(
+                    this.unit.id(),
+                    this.unit.type(),
+                  ),
+                );
+              }
+            }}
+            class="upgrade-button"
+            title="${translateText("unit_info_modal.upgrade")}"
+            style="width: 100px; height: 32px; display: ${this.game.unitInfo(
+              this.unit.type(),
+            ).upgradable
+              ? "block"
+              : "none"};"
+          >
+            ${translateText("unit_info_modal.upgrade")}
+          </button>
           <button
             @click=${() => {
               this.onCloseStructureModal();
diff --git a/src/core/Schemas.ts b/src/core/Schemas.ts
index e4fff95a6..73680517a 100644
--- a/src/core/Schemas.ts
+++ b/src/core/Schemas.ts
@@ -34,7 +34,8 @@ export type Intent =
   | EmbargoIntent
   | QuickChatIntent
   | MoveWarshipIntent
-  | MarkDisconnectedIntent;
+  | MarkDisconnectedIntent
+  | UpgradeStructureIntent;
 
 export type AttackIntent = z.infer<typeof AttackIntentSchema>;
 export type CancelAttackIntent = z.infer<typeof CancelAttackIntentSchema>;
@@ -55,6 +56,9 @@ export type TargetTroopRatioIntent = z.infer<
   typeof TargetTroopRatioIntentSchema
 >;
 export type BuildUnitIntent = z.infer<typeof BuildUnitIntentSchema>;
+export type UpgradeStructureIntent = z.infer<
+  typeof UpgradeStructureIntentSchema
+>;
 export type MoveWarshipIntent = z.infer<typeof MoveWarshipIntentSchema>;
 export type QuickChatIntent = z.infer<typeof QuickChatIntentSchema>;
 export type MarkDisconnectedIntent = z.infer<
@@ -178,6 +182,7 @@ const BaseIntentSchema = z.object({
     "emoji",
     "troop_ratio",
     "build_unit",
+    "upgrade_structure",
     "embargo",
     "move_warship",
   ]),
@@ -266,6 +271,12 @@ export const BuildUnitIntentSchema = BaseIntentSchema.extend({
   y: z.number(),
 });
 
+export const UpgradeStructureIntentSchema = BaseIntentSchema.extend({
+  type: z.literal("upgrade_structure"),
+  unit: z.nativeEnum(UnitType),
+  unitId: z.number(),
+});
+
 export const CancelAttackIntentSchema = BaseIntentSchema.extend({
   type: z.literal("cancel_attack"),
   attackID: z.string(),
@@ -316,6 +327,7 @@ const IntentSchema = z.union([
   DonateTroopIntentSchema,
   TargetTroopRatioIntentSchema,
   BuildUnitIntentSchema,
+  UpgradeStructureIntentSchema,
   EmbargoIntentSchema,
   MoveWarshipIntentSchema,
   QuickChatIntentSchema,
diff --git a/src/core/StatsSchemas.ts b/src/core/StatsSchemas.ts
index a9ef657b4..e9a643766 100644
--- a/src/core/StatsSchemas.ts
+++ b/src/core/StatsSchemas.ts
@@ -83,6 +83,7 @@ export const OTHER_INDEX_BUILT = 0; // Structures and warships built
 export const OTHER_INDEX_DESTROY = 1; // Structures and warships destroyed
 export const OTHER_INDEX_CAPTURE = 2; // Structures captured
 export const OTHER_INDEX_LOST = 3; // Structures/warships destroyed/captured by others
+export const OTHER_INDEX_UPGRADE = 4; // Structures upgraded
 
 const BigIntStringSchema = z.preprocess((val) => {
   if (typeof val === "string" && /^\d+$/.test(val)) return BigInt(val);
diff --git a/src/core/configuration/DefaultConfig.ts b/src/core/configuration/DefaultConfig.ts
index dc88b18c4..cc36057b7 100644
--- a/src/core/configuration/DefaultConfig.ts
+++ b/src/core/configuration/DefaultConfig.ts
@@ -347,6 +347,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
+          upgradable: true,
         };
       case UnitType.AtomBomb:
         return {
@@ -390,6 +391,7 @@ export class DefaultConfig implements Config {
               : 1_000_000n,
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 10 * 10,
+          upgradable: true,
         };
       case UnitType.DefensePost:
         return {
@@ -406,6 +408,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 5 * 10,
+          upgradable: true,
         };
       case UnitType.SAMLauncher:
         return {
@@ -422,6 +425,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 30 * 10,
+          upgradable: true,
         };
       case UnitType.City:
         return {
@@ -439,6 +443,7 @@ export class DefaultConfig implements Config {
                 ),
           territoryBound: true,
           constructionDuration: this.instantBuild() ? 0 : 2 * 10,
+          upgradable: true,
         };
       case UnitType.Construction:
         return {
@@ -666,7 +671,11 @@ export class DefaultConfig implements Config {
       player.type() === PlayerType.Human && this.infiniteTroops()
         ? 1_000_000_000
         : 2 * (Math.pow(player.numTilesOwned(), 0.6) * 1000 + 50000) +
-          player.units(UnitType.City).length * this.cityPopulationIncrease();
+          player
+            .units(UnitType.City)
+            .map((city) => city.level())
+            .reduce((a, b) => a + b, 0) *
+            this.cityPopulationIncrease();
 
     if (player.type() === PlayerType.Bot) {
       return maxPop / 2;
@@ -761,8 +770,7 @@ export class DefaultConfig implements Config {
   }
 
   structureMinDist(): number {
-    // TODO: Increase this to ~15 once upgradable structures are implemented.
-    return 1;
+    return 15;
   }
 
   shellLifetime(): number {
diff --git a/src/core/execution/ExecutionManager.ts b/src/core/execution/ExecutionManager.ts
index a333d95ec..9640b8d5e 100644
--- a/src/core/execution/ExecutionManager.ts
+++ b/src/core/execution/ExecutionManager.ts
@@ -24,6 +24,7 @@ import { SetTargetTroopRatioExecution } from "./SetTargetTroopRatioExecution";
 import { SpawnExecution } from "./SpawnExecution";
 import { TargetPlayerExecution } from "./TargetPlayerExecution";
 import { TransportShipExecution } from "./TransportShipExecution";
+import { UpgradeStructureExecution } from "./UpgradeStructureExecution";
 
 export class Executor {
   // private random = new PseudoRandom(999)
@@ -114,6 +115,8 @@ export class Executor {
           this.mg.ref(intent.x, intent.y),
           intent.unit,
         );
+      case "upgrade_structure":
+        return new UpgradeStructureExecution(player, intent.unitId);
       case "quick_chat":
         return new QuickChatExecution(
           player,
diff --git a/src/core/execution/MissileSiloExecution.ts b/src/core/execution/MissileSiloExecution.ts
index 7fd9459d8..8ff9fabc3 100644
--- a/src/core/execution/MissileSiloExecution.ts
+++ b/src/core/execution/MissileSiloExecution.ts
@@ -34,10 +34,20 @@ export class MissileSiloExecution implements Execution {
       }
     }
 
-    const cooldown = this.silo.ticksLeftInCooldown();
+    const frontTime = this.silo.ticksLeftInCooldown();
+    if (frontTime === undefined) {
+      return;
+    }
+
+    const cooldown =
+      this.mg.config().SiloCooldown() - (this.mg.ticks() - frontTime);
     if (typeof cooldown === "number" && cooldown >= 0) {
       this.silo.touch();
     }
+
+    if (cooldown <= 0) {
+      this.silo.reloadMissile();
+    }
   }
 
   isActive(): boolean {
diff --git a/src/core/execution/SAMLauncherExecution.ts b/src/core/execution/SAMLauncherExecution.ts
index 783c2b1f4..e183c67cf 100644
--- a/src/core/execution/SAMLauncherExecution.ts
+++ b/src/core/execution/SAMLauncherExecution.ts
@@ -155,11 +155,6 @@ export class SAMLauncherExecution implements Execution {
       target = this.getSingleTarget();
     }
 
-    const cooldown = this.sam.ticksLeftInCooldown();
-    if (typeof cooldown === "number" && cooldown >= 0) {
-      this.sam.touch();
-    }
-
     const isSingleTarget = target && !target.targetedBySAM();
     if (
       (isSingleTarget || mirvWarheadTargets.length > 0) &&
@@ -204,6 +199,21 @@ export class SAMLauncherExecution implements Execution {
         }
       }
     }
+
+    const frontTime = this.sam.ticksLeftInCooldown();
+    if (frontTime === undefined) {
+      return;
+    }
+
+    const cooldown =
+      this.mg.config().SAMCooldown() - (this.mg.ticks() - frontTime);
+    if (typeof cooldown === "number" && cooldown >= 0) {
+      this.sam.touch();
+    }
+
+    if (cooldown <= 0) {
+      this.sam.reloadMissile();
+    }
   }
 
   isActive(): boolean {
diff --git a/src/core/execution/UpgradeStructureExecution.ts b/src/core/execution/UpgradeStructureExecution.ts
new file mode 100644
index 000000000..19f14ff4c
--- /dev/null
+++ b/src/core/execution/UpgradeStructureExecution.ts
@@ -0,0 +1,44 @@
+import { Execution, Game, Player, Unit } from "../game/Game";
+
+export class UpgradeStructureExecution implements Execution {
+  private structure: Unit | undefined;
+  private cost: bigint;
+
+  constructor(
+    private player: Player,
+    private unitId: number,
+  ) {}
+
+  init(mg: Game, ticks: number): void {
+    this.structure = this.player
+      .units()
+      .find((unit) => unit.id() === this.unitId);
+
+    if (this.structure === undefined) {
+      console.warn(`structure is undefined`);
+      return;
+    }
+    if (!this.structure.info().upgradable) {
+      console.warn(`unit type ${this.structure} cannot be upgraded`);
+      return;
+    }
+    this.cost = this.structure.info().cost(this.player);
+    if (this.player.gold() < this.cost) {
+      return;
+    }
+    this.player.upgradeUnit(this.structure);
+    return;
+  }
+
+  tick(ticks: number): void {
+    return;
+  }
+
+  isActive(): boolean {
+    return false;
+  }
+
+  activeDuringSpawnPhase(): boolean {
+    return false;
+  }
+}
diff --git a/src/core/game/Game.ts b/src/core/game/Game.ts
index 6e89dee63..8e30cdafb 100644
--- a/src/core/game/Game.ts
+++ b/src/core/game/Game.ts
@@ -130,6 +130,7 @@ export interface UnitInfo {
   maxHealth?: number;
   damage?: number;
   constructionDuration?: number;
+  upgradable?: boolean;
 }
 
 export enum UnitType {
@@ -385,8 +386,9 @@ export interface Unit {
 
   // SAMs & Missile Silos
   launch(): void;
-  ticksLeftInCooldown(): Tick | undefined;
+  reloadMissile(): void;
   isInCooldown(): boolean;
+  ticksLeftInCooldown(): Tick | undefined;
 
   // Trade Ships
   setSafeFromPirates(): void; // Only for trade ships
@@ -396,6 +398,10 @@ export interface Unit {
   constructionType(): UnitType | null;
   setConstructionType(type: UnitType): void;
 
+  // Upgradable Structures
+  level(): number;
+  increaseLevel(): void;
+
   // Warships
   setPatrolTile(tile: TileRef): void;
   patrolTile(): TileRef | undefined;
@@ -471,6 +477,7 @@ export interface Player {
     spawnTile: TileRef,
     params: UnitParams<T>,
   ): Unit;
+  upgradeUnit(unit: Unit): void;
 
   captureUnit(unit: Unit): void;
 
diff --git a/src/core/game/GameUpdates.ts b/src/core/game/GameUpdates.ts
index 4a67f55e5..3bcbf9ce8 100644
--- a/src/core/game/GameUpdates.ts
+++ b/src/core/game/GameUpdates.ts
@@ -80,7 +80,9 @@ export interface UnitUpdate {
   targetTile?: TileRef; // Only for nukes
   health?: number;
   constructionType?: UnitType;
-  ticksLeftInCooldown?: Tick;
+  missileTimerQueue: number[];
+  readyMissileCount: number;
+  level: number;
 }
 
 export interface AttackUpdate {
diff --git a/src/core/game/GameView.ts b/src/core/game/GameView.ts
index aaaaa591c..4b7b8df41 100644
--- a/src/core/game/GameView.ts
+++ b/src/core/game/GameView.ts
@@ -112,11 +112,13 @@ export class UnitView {
     return this.data.targetTile;
   }
   ticksLeftInCooldown(): Tick | undefined {
-    return this.data.ticksLeftInCooldown;
+    return this.data.missileTimerQueue?.[0];
   }
-  isCooldown(): boolean {
-    if (this.data.ticksLeftInCooldown === undefined) return false;
-    return this.data.ticksLeftInCooldown > 0;
+  isInCooldown(): boolean {
+    return this.data.readyMissileCount === 0;
+  }
+  level(): number {
+    return this.data.level;
   }
 }
 
diff --git a/src/core/game/PlayerImpl.ts b/src/core/game/PlayerImpl.ts
index 7a528b284..3cbc07ae0 100644
--- a/src/core/game/PlayerImpl.ts
+++ b/src/core/game/PlayerImpl.ts
@@ -754,6 +754,12 @@ export class PlayerImpl implements Player {
     return b;
   }
 
+  upgradeUnit(unit: Unit) {
+    const cost = this.mg.unitInfo(unit.type()).cost(this);
+    this.removeGold(cost);
+    unit.increaseLevel();
+  }
+
   public buildableUnits(tile: TileRef): BuildableUnit[] {
     const validTiles = this.validStructureSpawnTiles(tile);
     return Object.values(UnitType).map((u) => {
diff --git a/src/core/game/Stats.ts b/src/core/game/Stats.ts
index e4f95758b..c3af26c7e 100644
--- a/src/core/game/Stats.ts
+++ b/src/core/game/Stats.ts
@@ -85,6 +85,9 @@ export interface Stats {
   // Player captures a unit of type
   unitCapture(player: Player, type: OtherUnitType): void;
 
+  // Player upgrades a unit of type
+  unitUpgrade(player: Player, type: OtherUnitType): void;
+
   // Player destroys a unit of type
   unitDestroy(player: Player, type: OtherUnitType): void;
 
diff --git a/src/core/game/StatsImpl.ts b/src/core/game/StatsImpl.ts
index 1a1a7618d..88469b7b8 100644
--- a/src/core/game/StatsImpl.ts
+++ b/src/core/game/StatsImpl.ts
@@ -20,6 +20,7 @@ import {
   OTHER_INDEX_CAPTURE,
   OTHER_INDEX_DESTROY,
   OTHER_INDEX_LOST,
+  OTHER_INDEX_UPGRADE,
   OtherUnitType,
   PlayerStats,
   unitTypeToBombUnit,
@@ -234,6 +235,10 @@ export class StatsImpl implements Stats {
     this._addOtherUnit(player, type, OTHER_INDEX_CAPTURE, 1);
   }
 
+  unitUpgrade(player: Player, type: OtherUnitType): void {
+    this._addOtherUnit(player, type, OTHER_INDEX_UPGRADE, 1);
+  }
+
   unitDestroy(player: Player, type: OtherUnitType): void {
     this._addOtherUnit(player, type, OTHER_INDEX_DESTROY, 1);
   }
diff --git a/src/core/game/UnitImpl.ts b/src/core/game/UnitImpl.ts
index e68178eee..85ff736c7 100644
--- a/src/core/game/UnitImpl.ts
+++ b/src/core/game/UnitImpl.ts
@@ -26,8 +26,10 @@ export class UnitImpl implements Unit {
   private _constructionType: UnitType | undefined;
   private _lastOwner: PlayerImpl | null = null;
   private _troops: number;
-  private _cooldownStartTick: Tick | null = null;
+  private _missileTimerQueue: number[] = [];
+  private _readyMissileCount: number = 1;
   private _patrolTile: TileRef | undefined;
+  private _level: number = 1;
   constructor(
     private _type: UnitType,
     private mg: GameImpl,
@@ -104,7 +106,9 @@ export class UnitImpl implements Unit {
       constructionType: this._constructionType,
       targetUnitId: this._targetUnit?.id() ?? undefined,
       targetTile: this.targetTile() ?? undefined,
-      ticksLeftInCooldown: this.ticksLeftInCooldown() ?? undefined,
+      missileTimerQueue: this._missileTimerQueue,
+      readyMissileCount: this._readyMissileCount,
+      level: this.level(),
     };
   }
 
@@ -267,30 +271,23 @@ export class UnitImpl implements Unit {
   }
 
   launch(): void {
-    this._cooldownStartTick = this.mg.ticks();
+    this._missileTimerQueue.push(this.mg.ticks());
+    this._readyMissileCount--;
     this.mg.addUpdate(this.toUpdate());
   }
 
   ticksLeftInCooldown(): Tick | undefined {
-    let cooldownDuration = 0;
-    if (this.type() === UnitType.SAMLauncher) {
-      cooldownDuration = this.mg.config().SAMCooldown();
-    } else if (this.type() === UnitType.MissileSilo) {
-      cooldownDuration = this.mg.config().SiloCooldown();
-    } else {
-      return undefined;
-    }
-
-    if (!this._cooldownStartTick) {
-      return undefined;
-    }
-
-    return cooldownDuration - (this.mg.ticks() - this._cooldownStartTick);
+    return this._missileTimerQueue[0];
   }
 
   isInCooldown(): boolean {
-    const ticksLeft = this.ticksLeftInCooldown();
-    return ticksLeft !== undefined && ticksLeft > 0;
+    return this._readyMissileCount === 0;
+  }
+
+  reloadMissile(): void {
+    this._missileTimerQueue.shift();
+    this._readyMissileCount++;
+    this.mg.addUpdate(this.toUpdate());
   }
 
   setTargetTile(targetTile: TileRef | undefined) {
@@ -335,4 +332,16 @@ export class UnitImpl implements Unit {
       this.mg.config().safeFromPiratesCooldownMax()
     );
   }
+
+  level(): number {
+    return this._level;
+  }
+
+  increaseLevel(): void {
+    this._level++;
+    if ([UnitType.MissileSilo, UnitType.SAMLauncher].includes(this.type())) {
+      this._readyMissileCount++;
+    }
+    this.mg.addUpdate(this.toUpdate());
+  }
 }
diff --git a/tests/MissileSilo.test.ts b/tests/MissileSilo.test.ts
index 04d708546..02e5875e6 100644
--- a/tests/MissileSilo.test.ts
+++ b/tests/MissileSilo.test.ts
@@ -1,5 +1,6 @@
 import { NukeExecution } from "../src/core/execution/NukeExecution";
 import { SpawnExecution } from "../src/core/execution/SpawnExecution";
+import { UpgradeStructureExecution } from "../src/core/execution/UpgradeStructureExecution";
 import {
   Game,
   Player,
@@ -9,7 +10,7 @@ import {
 } from "../src/core/game/Game";
 import { TileRef } from "../src/core/game/GameMap";
 import { setup } from "./util/Setup";
-import { constructionExecution } from "./util/utils";
+import { constructionExecution, executeTicks } from "./util/utils";
 
 let game: Game;
 let attacker: Player;
@@ -85,7 +86,21 @@ describe("MissileSilo", () => {
       ).toBeTruthy();
     }
 
-    game.executeNextTick();
+    executeTicks(game, 2);
+
     expect(attacker.units(UnitType.MissileSilo)[0].isInCooldown()).toBeFalsy();
   });
+
+  test("missilesilo should have increased level after upgrade", async () => {
+    expect(attacker.units(UnitType.MissileSilo)[0].level()).toEqual(1);
+
+    const upgradeStructureExecution = new UpgradeStructureExecution(
+      attacker,
+      attacker.units(UnitType.MissileSilo)[0].id(),
+    );
+    game.addExecution(upgradeStructureExecution);
+    executeTicks(game, 2);
+
+    expect(attacker.units(UnitType.MissileSilo)[0].level()).toEqual(2);
+  });
 });
diff --git a/tests/SAM.test.ts b/tests/SAM.test.ts
index d3f209673..ef3458940 100644
--- a/tests/SAM.test.ts
+++ b/tests/SAM.test.ts
@@ -1,6 +1,7 @@
 import { NukeExecution } from "../src/core/execution/NukeExecution";
 import { SAMLauncherExecution } from "../src/core/execution/SAMLauncherExecution";
 import { SpawnExecution } from "../src/core/execution/SpawnExecution";
+import { UpgradeStructureExecution } from "../src/core/execution/UpgradeStructureExecution";
 import {
   Game,
   Player,
@@ -94,6 +95,7 @@ describe("SAM", () => {
 
   test("sam should cooldown as long as configured", async () => {
     const sam = defender.buildUnit(UnitType.SAMLauncher, game.ref(1, 1), {});
+
     game.addExecution(new SAMLauncherExecution(defender, null, sam));
     expect(sam.isInCooldown()).toBeFalsy();
     const nuke = attacker.buildUnit(UnitType.AtomBomb, game.ref(1, 2), {
@@ -103,6 +105,7 @@ describe("SAM", () => {
     executeTicks(game, 3);
 
     expect(nuke.isActive()).toBeFalsy();
+
     for (let i = 0; i < game.config().SAMCooldown() - 3; i++) {
       game.executeNextTick();
       expect(sam.isInCooldown()).toBeTruthy();
@@ -161,4 +164,18 @@ describe("SAM", () => {
     expect(sam1.isInCooldown()).toBeFalsy();
     expect(sam2.isInCooldown()).toBeTruthy();
   });
+
+  test("SAM should have increased level after upgrade", async () => {
+    defender.buildUnit(UnitType.SAMLauncher, game.ref(1, 1), {});
+    expect(defender.units(UnitType.SAMLauncher)[0].level()).toEqual(1);
+
+    const upgradeStructureExecution = new UpgradeStructureExecution(
+      defender,
+      defender.units(UnitType.SAMLauncher)[0].id(),
+    );
+    game.addExecution(upgradeStructureExecution);
+    executeTicks(game, 2);
+
+    expect(defender.units(UnitType.SAMLauncher)[0].level()).toEqual(2);
+  });
 });