Earlier this month the Pentagon entered a new phase of its air campaign in Iraq against the Islamic State when it announced that AH-64 Apache helicopters would assist beleaguered Iraqi and Kurdish ground forces. Almost simultaneously on Twitter, the Islamic State released a how-to guide on how to shoot down the heavily armed aircraft with a man portable air defense system or MANPADS.

The Apache first entered service in 1986 and has undergone various iterations since. Its main armaments consist of a 30mm cannon and it can carry an assortment of missiles, including the vaunted Hellfire.

The Islamic State, seemingly well aware of the aircraft’s capabilities, notes in its guide that the Apache’s pilot and gunner are well protected from ground fire and shrapnel with reinforced armor plating. The best way to shoot down the helicopter, the guide says, is with advanced MANPADS like the American FIM-92 Stinger and the Russian SA-16 and SA-18.

The Islamic State manual, first reported on by the International Business Times and posted recently in full on New York Times reporter C.J Chivers’ website, is a telling example of how the Islamic State marries propaganda and battlefield tactics.

While the Stinger has never been documented in Islamic State hands, both the SA-16 and SA-18 have been sighted, albeit in limited quantities, with armed groups in Syria according to a report released by Small Arms Survey in August. Additionally, the Islamic State released still images last month after claiming responsibility for shooting down an Iraqi Mi-35 helicopter north of Baghdad with a Chinese FN-6 MANPADS.

The Mi-35, while Russian built, has many of the same capabilities as the Apache including missile detection systems and counter measures. The Islamic State’s possession of MANPADS has not been officially confirmed, but State Department spokesperson Jen Psaki said Monday the U.S. government is “assessing these claims.”

There’s clearly significant potential threat to aviation operating in Iraqi and Syrian airspace due to ongoing fighting,” Psaki said. “But – and of particular concern is our advanced conventional weapons like MANPADS, but we don’t have confirmation of this at that time – at this time.”

The Islamic State has claimed to have destroyed a number of aircraft in both Iraq and Syria, but only in recent months has footage appeared of the group wielding more advanced missiles like the FN-6.

The FN-6 can hit targets flying at around 11,000 feet while the SA-18 has an effective range upwards of 18,000 feet. This puts Apaches flying at low altitude within striking distance along with other low flying aircraft, like the C-130 transport planes that are being used to resupply Kurdish and Iraqi forces in the region. Yet, while both aircraft might be within engagement range, both the C-130 and Apache have countermeasures to temporarily defeat threats posed by heat-seeking missiles.

The guide goes on to emphasize methods for employing MANPADS, noting that the gunner should carefully select his firing position in order to minimize the dust cloud generated by the missile launch and that he should take only five to ten seconds to target the helicopter before firing so it has less time to detect in the incoming missile. If possible, the guide adds, two missiles should be fired ten seconds apart to increase the likeliness of hitting the target.

Firing two missiles at once, known as volley fire, increases the likelihood of a crash if both missiles hit. Additionally, having two missiles in various stages of flight make it increasingly more difficult for the pilot to outmaneuver them.

Other parts of the document also highlight what Islamic State fighters should do after shooting down the helicopter. This includes destroying spent MANPADS tubes, using a sniper to shoot aircrew members who manage to get clear of the wreckage and using “4-6 missiles” to shoot other aircraft as they attempt to secure the first crash site.