Turkey has repeated calls for US forces to take direct action to stop Kurdish rebels, the PKK, using bases in Iraq to launch attacks against Turkey.
Prime Minister Recep Tayyip Erdogan said there was a limit to Turkey’s tolerance and suggested that if the US did not respond, Turkey would.
He said his country was within its rights under international law to take action to defend itself.
His comments come amid an upsurge in attacks by the PKK.
The rebels called off a five-year unilateral ceasefire last summer.
Turkey suspects them of being behind the kidnap of the mayor of Yayladere district in south-eastern Turkey on Wednesday.
Washington recently promised to step up monitoring of the PKK’s activities in Northern Iraq.
But Mr Erdogan told The Times newspaper, during a visit to London, that he expected nothing short of direct intervention. At the moment, he said, Turkey did not see the effort by Washington that it expected and had expressed that view to the Americans.
There was a limit to Ankara’s tolerance, he said – Turkey was within its rights under international law to defend itself from attack.
In the 1990s, Ankara took advantage of a power vacuum in Kurdish-administered northern Iraq to launch a series of cross-border operations against the PKK, some involving many thousands of troops.
The US recently warned Ankara against such raids, saying they could have unintended consequences.
The PKK is branded a terrorist organisation by Turkey, the United States and the European Union.
However, US forces – overstretched by the violence in central and southern Iraq – have avoided promising to pursue the PKK in the relatively peaceful north.
Ankara believes something must be done. There are now daily clashes between the PKK and Turkish troops; the group is again kidnapping Turkish soldiers and local officials and Turkey has blamed the organisation for a series of recent bomb explosions in tourist resorts.