diff --git a/src/client/graphics/layers/PlayerActionHandler.ts b/src/client/graphics/layers/PlayerActionHandler.ts
index 54714cadbf..2ccaef0459 100644
--- a/src/client/graphics/layers/PlayerActionHandler.ts
+++ b/src/client/graphics/layers/PlayerActionHandler.ts
@@ -3,6 +3,7 @@ import { PlayerActions } from "../../../core/game/Game";
 import { TileRef } from "../../../core/game/GameMap";
 import { PlayerView } from "../../../core/game/GameView";
 import {
+  SendAllianceExtensionIntentEvent,
   SendAllianceRequestIntentEvent,
   SendAttackIntentEvent,
   SendBoatAttackIntentEvent,
@@ -63,6 +64,10 @@ export class PlayerActionHandler {
     this.eventBus.emit(new SendAllianceRequestIntentEvent(player, recipient));
   }
 
+  handleExtendAlliance(recipient: PlayerView) {
+    this.eventBus.emit(new SendAllianceExtensionIntentEvent(recipient));
+  }
+
   handleBreakAlliance(player: PlayerView, recipient: PlayerView) {
     this.eventBus.emit(new SendBreakAllianceIntentEvent(player, recipient));
   }
diff --git a/src/client/graphics/layers/RadialMenuElements.ts b/src/client/graphics/layers/RadialMenuElements.ts
index aeafdf8a10..d7ced8acb2 100644
--- a/src/client/graphics/layers/RadialMenuElements.ts
+++ b/src/client/graphics/layers/RadialMenuElements.ts
@@ -209,6 +209,20 @@ const allyRequestElement: MenuElement = {
   },
 };
 
+const allyExtendElement: MenuElement = {
+  id: "ally_extend",
+  name: "extend",
+  disabled: (params: MenuElementParams) => false,
+  displayed: (params: MenuElementParams) =>
+    !!params.playerActions?.interaction?.canExtendAlliance,
+  color: COLORS.boat,
+  icon: allianceIcon,
+  action: (params: MenuElementParams) => {
+    params.playerActionHandler.handleExtendAlliance(params.selected!);
+    params.closeMenu();
+  },
+};
+
 const allyBreakElement: MenuElement = {
   id: "ally_break",
   name: "break",
@@ -624,13 +638,16 @@ export const rootMenuElement: MenuElement = {
       tileOwner.isPlayer() &&
       (tileOwner as PlayerView).id() === params.myPlayer.id();
 
+    const canExtendAlliance =
+      params.playerActions.interaction?.canExtendAlliance;
+
     const menuItems: (MenuElement | null)[] = [
       infoMenuElement,
       ...(isOwnTerritory
         ? [deleteUnitElement, allyRequestElement, buildMenuElement]
         : [
             isAllied ? allyBreakElement : boatMenuElement,
-            allyRequestElement,
+            canExtendAlliance ? allyExtendElement : allyRequestElement,
             isFriendlyTarget(params) && !isDisconnectedTarget(params)
               ? donateGoldRadialElement
               : attackMenuElement,
diff --git a/src/core/GameRunner.ts b/src/core/GameRunner.ts
index 0f93a94f68..e9be9a768f 100644
--- a/src/core/GameRunner.ts
+++ b/src/core/GameRunner.ts
@@ -207,6 +207,7 @@ export class GameRunner {
         canSendEmoji: player.canSendEmoji(other),
         canTarget: player.canTarget(other),
         canSendAllianceRequest: player.canSendAllianceRequest(other),
+        canExtendAlliance: player.canExtendAlliance(other),
         canBreakAlliance: player.isAlliedWith(other),
         canDonateGold: player.canDonateGold(other),
         canDonateTroops: player.canDonateTroops(other),
diff --git a/src/core/game/AllianceImpl.ts b/src/core/game/AllianceImpl.ts
index fa74ca766c..5b60bd59a9 100644
--- a/src/core/game/AllianceImpl.ts
+++ b/src/core/game/AllianceImpl.ts
@@ -62,6 +62,13 @@ export class AllianceImpl implements MutableAlliance {
     );
   }
 
+  agreedToExtend(player: Player): boolean {
+    return (
+      (this.requestor_ === player && this.extensionRequestedRequestor_) ||
+      (this.recipient_ === player && this.extensionRequestedRecipient_)
+    );
+  }
+
   public id(): number {
     return this.id_;
   }
diff --git a/src/core/game/Game.ts b/src/core/game/Game.ts
index f291e11214..9c8e5730e4 100644
--- a/src/core/game/Game.ts
+++ b/src/core/game/Game.ts
@@ -450,6 +450,8 @@ export interface MutableAlliance extends Alliance {
   id(): number;
   extend(): void;
   onlyOneAgreedToExtend(): boolean;
+
+  agreedToExtend(player: Player): boolean;
 }
 
 export class PlayerInfo {
@@ -658,6 +660,7 @@ export interface Player {
   isAlliedWith(other: Player): boolean;
   allianceWith(other: Player): MutableAlliance | null;
   canSendAllianceRequest(other: Player): boolean;
+  canExtendAlliance(other: Player): boolean;
   breakAlliance(alliance: Alliance): void;
   createAllianceRequest(recipient: Player): AllianceRequest | null;
   betrayals(): number;
@@ -858,6 +861,7 @@ export interface PlayerInteraction {
   sharedBorder: boolean;
   canSendEmoji: boolean;
   canSendAllianceRequest: boolean;
+  canExtendAlliance: boolean;
   canBreakAlliance: boolean;
   canTarget: boolean;
   canDonateGold: boolean;
diff --git a/src/core/game/PlayerImpl.ts b/src/core/game/PlayerImpl.ts
index fae23df8eb..c603bbca81 100644
--- a/src/core/game/PlayerImpl.ts
+++ b/src/core/game/PlayerImpl.ts
@@ -400,6 +400,38 @@ export class PlayerImpl implements Player {
     );
   }
 
+  canExtendAlliance(other: Player): boolean {
+    if (other === this) {
+      return false;
+    }
+
+    if (this.isDisconnected() || other.isDisconnected()) {
+      // Disconnected players are marked as not-friendly even if they are allies,
+      // so we need to return early if either player is disconnected.
+      // Otherwise we could end up sending an alliance extension to someone
+      // we are already allied with.
+      return false;
+    }
+    if (!this.allianceWith(other) || !this.isAlive() || !other.isAlive()) {
+      return false;
+    }
+
+    const alliance = this.allianceWith(other);
+
+    if (!alliance) {
+      return false;
+    }
+
+    if (
+      alliance.expiresAt() >
+      this.mg.ticks() + this.mg.config().allianceExtensionPromptOffset()
+    ) {
+      return false;
+    }
+
+    return !alliance.agreedToExtend(this);
+  }
+
   canSendAllianceRequest(other: Player): boolean {
     if (other === this) {
       return false;