diff --git a/binaries/data/mods/public/simulation/ai/petra/defenseArmy.js b/binaries/data/mods/public/simulation/ai/petra/defenseArmy.js
index 3438e5f3b4..4ba951d182 100644
--- a/binaries/data/mods/public/simulation/ai/petra/defenseArmy.js
+++ b/binaries/data/mods/public/simulation/ai/petra/defenseArmy.js
@@ -29,9 +29,9 @@ function getFoeInfo(gameState, foeEntities)
 			if (orderData && orderData.length && orderData[0].target)
 				attackTarget = orderData[0].target;
 		}
-		// "heavy" and "access" are filled lazily.
+		// "heavy", "access" and the entries of "canAttack" are filled lazily.
 		info.push({ "id": id, "ent": eEnt, "position": position, "attackTarget": attackTarget,
-			"heavy": undefined, "access": undefined });
+			"capturable": eEnt.isCapturable(), "canAttack": new Map(), "heavy": undefined, "access": undefined });
 	}
 	return info;
 }
@@ -346,6 +346,7 @@ export class DefenseArmy
 		const pos = ent.position();
 		if (!pos)
 			return false;
+		const template = ent.templateName();
 
 		// try to return its resources, and if any, the attack order will be queued
 		const queued = returnResources(gameState, ent);
@@ -359,7 +360,15 @@ export class DefenseArmy
 		for (const foe of this.foeInfo)
 		{
 			const eEnt = foe.ent;
-			if (!ent.canAttackTarget(eEnt, allowCapture(gameState, ent, eEnt)))
+			// For a foe which is not capturable, allowCapture has no effect, so the result only depends on the template.
+			let canAttack = foe.canAttack.get(template);
+			if (canAttack === undefined)
+			{
+				canAttack = ent.canAttackTarget(eEnt, allowCapture(gameState, ent, eEnt));
+				if (!foe.capturable)
+					foe.canAttack.set(template, canAttack);
+			}
+			if (!canAttack)
 				continue;
 
 			if (foe.attackTarget === entID)