Davutoglu also said Turkey would tighten security across the country, especially the capital, after a car laden with explosives was detonated near military buses in Ankara on February 17, killing 28 people.

Turkey says the Syrian Kurdish YPG, which the United States is backing in the fight against Islamic State in Syria, was involved in the bombing, working with the outlawed Kurdistan Workers Party (PKK).

Washington, which does not consider the YPG a terrorist organization, has said it is not in a position to confirm or deny Ankara's charge the militia was behind the bombing.

"The only thing we expect from our U.S. ally is to support Turkey with no ifs or buts," Davutoglu told a news conference following a five-hour security meeting with members of his cabinet and other officials.

Turkish Prime Minister Ahmet Davutoglu (C) prays during his visit to the site of February 17's suicide bomb attack in Ankara, Turkey February 19, 2016, as he is flanked by Interior Minister Efkan Ala (L), Defence Minister Ismet Yilmaz (R) and Governor of Ankara Mehmet Kiliclar...
"If 28 Turkish lives have been claimed through a terrorist attack we can only expect them to say any threat against Turkey is a threat against them."

The disagreement over the YPG risks driving a wedge between the NATO allies at a critical point in Syria's civil war, as the United States pursues intensive talks with Syrian ally Russia to bring about a "cessation of hostilities".

The Kurdistan Freedom Hawks (TAK), a group that once had links to the PKK, on February 19 claimed responsibility for the bombing. However, Davutoglu said that did not rule out the responsibility of the YPG, calling the TAK a "proxy" that claimed the bombing to shield the international reputation of the Syrian Kurdish fighters.