Spokeswoman Dana Perino called the outlawed Kurdistan Workers' Party (PKK) fighters "a threat" to Turkey, Iraq, and the United States but said Washington had urged Ankara to take "very targeted and limited" action against them.

But she declined to comment specifically on what the office of Massud Barzani, president of Iraq's northern Kurdish government, said was an incursion by around 500 Turkish soldiers. Turkey has declined to confirm the strike.

"Since there are conflicting reports, let's wait and see what is actually happening on the ground there before we comment. We have asked Turkey to keep the operations very targeted and limited," said Perino.

"I think we should wait until there's more concrete information from the ground in terms of how far the incursion was, how many people, who all was involved," said the spokeswoman.

"I can tell you that of course we are coordinating with the Turkish and Iraqi authorities in the area. The PKK is a threat to Turkey, to Iraq, and to the United States. So we continue to share information, share intelligence, with them (Turkish and Iraqi authorities)," said Perino.

"The Turks have moved forward with our coordination and in communication with the Iraqis in order to eradicate that threat," the spokeswoman said.