Turkey's parliament has given permission for the government to launch military operations into Iraq in pursuit of Kurdish rebels.
The vote was taken in defiance of pressure from the US and Iraq, which have called on Turkey for restraint.
Turkish Prime Minister Recep Tayyip Erdogan has said the motion does not mean a military operation is imminent.
But he said Turkey needed to be able to respond to a recent rise in bomb attacks blamed on PKK rebels from Iraq.
Turkish MPs backed him overwhelmingly, by 507 votes to 19.
As the vote was being counted, US President George W Bush strongly urged Turkey, a key ally, not to carry out the threatened action.