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(CNN) —  

US officials said they were “deeply concerned” after Turkey carried out a series of airstrikes Tuesday against US allies fighting ISIS in Syria and Iraq.

A senior US defense official told CNN that the US was given about one hour’s advance notice of the strikes by the Turkish military. The official added that no US or coalition advisers were in the vicinity.

Turkish warplanes struck targets in northern Syria and the area of Sinjar in northern Iraq. The Turkish armed forces issued a statement saying it had “neutralized” 70 PKK “terrorist” fighters – 40 in northern Iraq and 30 others in northeastern Syria.

The Turkish government has been conducting a decades-long fight against the PKK, a Kurdish separatist group that has carried out terrorist attacks in Turkey.

But Kurdish elements of the Syrian Democratic Forces, America’s primary Syrian ally in the fight against ISIS, and the Iraq-based Kurdish Peshmerga both said that they suffered casualties as well as a result of the airstrikes.

“We are very concerned, deeply concerned, that Turkey conducted airstrikes earlier today in northern Syria as well as northern Iraq without proper coordination either with the United States or the broader global coalition to defeat ISIS,” acting State Department spokesman Mark Toner told reporters Tuesday.

“We have expressed those concerns to the government of Turkey directly,” Toner added.

The Pentagon also released a statement on its concerns about the strikes.

“These ‎airstrikes were not approved by the Counter-ISIS Coalition and led to the unfortunate loss of life of our partner forces in the fight against ISIS, including the Kurdish Peshmerga,” Maj. Adrian Rankine-Galloway said.

A statement issued by the Peshmerga, the military arm of Iraq’s semi-autonomous Kurdistan Regional Government, said that five of its fighters were killed in the air raid and another nine wounded. The KRG blamed the nearby presence of PKK fighters for the casualties. The government of Iraq also protested the unilateral airstrikes by Turkey.

“Given the extraordinarily complex battle space in these areas, it is vital that Turkey and all partners in the defeat-ISIS effort coordinate their actions closely as we work together to maintain maximum pressure on ISIS and ensure the safety of all Coalition personnel in theater,” Rankine-Galloway said.

Turkey has long been opposed to the PKK, considered a terrorist organization by both Turkey and the US.

Ankara sees the PKK and the Kurdish forces in the Syrian Democratic Forces – known as the YPG – as closely linked, while the US views them as distinct organizations. The US sees the SDF as the most effective force fighting ISIS in Syria supporting its push on the city of Raqqa, ISIS’ self-declared capital.

“We recognize the threat the PKK poses to Turkey, but Turkey cannot pursue that fight at the expense of our common fight against terrorists that threaten us all,” Rankine-Galloway said.

While Turkey has struck PKK targets in Iraq in the past, Turkey’s latest military action comes days after President Donald Trump called President Recep Tayyip Erdogan to congratulate him after he prevailed in a closely contested referendum that granted his presidency additional powers. Trump’s congratulatory call stood out among Western leaders, many of whom struck a less laudatory tone over the controversial vote.

In the wake of his referendum victory, some US officials had hoped that Erdogan would be more flexible in cooperating with – or at least tolerating – US efforts aimed at backing the SDF offensive on Raqqa.