Fighters of the Islamic State of Iraq and Syria (ISIS) have reportedly laid their hands on sophisticated antiaircraft missile systems, raising with that the threat to air operations carried out by the U.S.-led coalition fighting against the group in Iraq and Syria.

Images from a video released by ISIS captured a fighter firing Chinese-made surface-to-air missile FN6 – and blowing an Iraqi army MI-35M during a battle in the oil-rich town of Baiji, north of Baghdad, according to the New York Times. Two crew members were reportedly killed as a result.

In several occasions antiaircraft missiles were used to shoot down Syrian army helicopters and even jets occasionally. Observers claim the Chinese shoulder-launched missiles were seized by ISIS militants from moderate rebels.

"The U.S. Apaches deployed to Baghdad will have countermeasures, but I cannot comment on whether they would be more effective than the ones on Iraq's new Mi-35Ms," Jeremy Binnie, of IHS Jane's, who spotted the ISIS video, told the Telegraph.

But the implications of ISIS’ use of antiaircraft weaponry are worrying military officials who warn that the missiles “are game changers out there.”

The video follows the release of an online Arabic-language guide reportedly made by ISIS outlining downing American military helicopters. The guide, which can be found on The New York Times’ journalist CJ Chivers’ website, called for the destruction of American Apache helicopters and provided specific operational instructions on how to use antiaircraft missiles, or MANPADS, and on how to go undetected.

“Choosing of the launching spot: Preferably somewhere high,” said the guide in Arabic. “The roof of a building or a hill that is on a solid surface [ground] in order to prevent the appearance of dust following launching.”

The United States, concerned about weapons going to extremists groups, has vehemently urged Qatar and other regional players to not supply Syrian rebels with “lethal” equipment in the past.

Last Update: Wednesday, 29 October 2014 KSA 23:37 - GMT 20:37