US military official: 'We were outraged' when Turkey pulled a fast one right after the anti-ISIS deal

An American military source told Fox News that US military leaders were "outraged" when Turkey began launching airstrikes against the Kurdish PKK in northern Iraq just hours after striking an anti-ISIS deal with the US.

"A Turkish officer came into the [the allied headquarters in the air war against ISIS] and announced that the strike would begin in 10 minutes and he needed all allied jets flying above Iraq to move south of Mosul immediately," the source said.

"We were outraged."

The US special forces stationed in northern Iraq advising and training Kurdish Peshmerga fighters had virtually no warning before Turkish jets started striking the mountains, where the PKK is headquartered.

"We had no idea who the Turkish fighters were, their call signs, what frequencies they were using, their altitude or what they were squawking [to identify the jets on radar]," the source explained.

Turkish military leaders asked coalition officers to reveal the trainers' specific whereabouts in order to avoid bombing them, but the officers flatly refused.

"No way we were giving that up," said the military source.

"If one of our guys got hit, the Turks would blame us. We gave the Turks large grids to avoid bombing. We could not risk having U.S. forces hit by Turkish bombs."

The confrontation highlights the tension growing between the US and Turkey, which became a reluctant ally in the fight against ISIS after years of turning a blind eye to the jihadis' illicit activity on its southern border.

On July 24, Ankara announced it would begin striking ISIS strongholds in northern Syria, and would allow the US to do the same from its Incirlik airbase in the southeast.

The ongoing bombing campaign against PKK strongholds in northern Iraq came as a surprise, but it probably shouldn't have: Turkey has long seen the PKK - a designated terrorist organization that waged a three-decade insurgency inside Turkey - as more of an existential threat than the Islamic State, which refrained from launching attacks inside Turkey even as its militants lived and operated along the border.

"There is no difference between PKK and Daesh," said Turkish Foreign Minister Mevlut Cavusoglu.

But Ankara's recent anti-terror sweep - which has resulted in the arrest of more than 800 suspected PKK members, compared with just over 100 suspected ISIS sympathizers - and the intensity of its bombing campaign in northern Iraq has made it clear that Turkey's main goal is not to prevent the consolidation of the Islamic State, but to halt the creation of an autonomous Kurdish state along its southern border.

The US, meanwhile, is moving away from its $500 million Syrian train-and-equip program and embracing a partnership with the YPG - Syrian Kurds who are closely allied with the PKK.

"To fully embrace a Kurdish force would complicate an already fragile strategy, two of the defense officials concluded," Nancy Youseff of The Daily Beast reports.

"The Turks ... would not welcome an emboldened Kurdish force on its southern border. Neither would many of America's Arab allies, who are also threatened by Kurdish sovereignty movements."

And if Turkey keeps going after PKK while not trying to provoke ISIS, "it will leave the US without a Syria strategy," geopolitical expert Ian Bremmer told Business Insider recently.

"Access to Incirlik airbase matters, but the additional bombing it enables will only help contain ISIS, not roll it back," Bremmer added. "And it will leave Washington without the improved relations with Ankara that the Obama administration is hoping for."