Bangladesh, May 27 -- The latest claim by Russian Federal Security Service (FSB) Director Aleksandr Bortnikov that Western intelligence agencies are preparing to use former ISIS militants against Iran is difficult to verify independently. Yet regardless of whether every aspect of the allegation proves accurate, the warning touches upon a dangerous reality that has repeatedly shaped modern geopolitics: major powers have often been tempted to use irregular armed groups as instruments of foreign policy, only to discover that such forces rarely remain under control.

According to Bortnikov, former Islamic State fighters and other jihadist militants are allegedly being transferred from detention facilities in Syria to specialized camps in nei...