In order to combat better the Mongol danger, Baybars established an intelligence service, which was based on secret operatives and informants in enemy territory. The information thus obtained was vital for the timely adoption of proper measures for the defence of the Sultanate. Baybars, however, did not stop at the mere gathering of information, but initiated assorted covert activities to weaken the Mongols, including assassination, disinformation to discredit opponents, and the cultivation of contacts with indigenous Muslim princes, officers and officials in the Īlkhānid state. This was in addition to the activities described in previous chapters which could also be placed under the rubric of “secret war,” such as the raids across the border, the burning of grasslands and the dispatch of Muslim rulers to reestablish their “kingdoms” (the Caliph al-Mustanṣir, al-Ṣāliḥ of Mosul and the “lord” of Irbil). Baybars's successors continued these activities until the end of the Mamluk–Īlkhānid war in 720/1320 and even after. As is to be expected, the sultans also used espionage and subterfuge against the Franks in Syria.

The Īlkhāns also tried their hand at both espionage and “dirty tricks.” In general, however, their efforts were not crowned with success, at least, according to the Mamluk sources, who probably only knew of such Mongol activities when they failed or those involved were caught.