Turkey's parliament has approved by a large majority a government request to allow troops to cross into northern Iraq to crush Kurdish rebels based there.
As parliament voted in Ankara by 507 votes to 19 in favour of the motion, US president George Bush said it would not be in Nato member Turkey's interests to send troops into Iraq and the Pentagon said it did not think Ankara had the appetite for such a move.
Washington fears a Turkish incursion could destabilise the most peaceful part of Iraq and possibly the wider region by encouraging others such as arch-foe Iran to intervene.
Iraq's government said today it would send a team to Ankara for further talks to find a peaceful solution to the crisis. Nato and the European Union also urged restraint.
Turkish prime minister Tayyip Erdogan has played down expectations of any imminent attack but the parliamentary vote gives Nato's second biggest army the legal basis to cross the mountainous border as and when it sees fit.
"What matters is what parliament has said," Mr Erdogan told reporters as he left the assembly after the vote.
Mr Erdogan is under heavy public pressure to act after a series of deadly attacks on its troops by the rebels of the outlawed Kurdistan Workers Party (PKK), who use northern Iraq as a base.
Ankara's stance has helped propel global oil prices to record highs above $88 a barrel, though they eased today.
Only the small pro-Kurdish Democratic Society Party (DTP) spoke against the motion, arguing that military action would worsen the economic plight of Turkey's mainly Kurdish southeast.
Mr Bush repeated US concerns. "They [Turkey] have had troops stationed there for quite a while. We don't think it's in their interest to send more troops in," he told a news conference.
Turkey keeps a relatively small contingent of troops at several bases in northern Iraq dating back to the time of previous offensives in the 1990s. Those offensives failed to eliminate the PKK guerrillas.
The European Commission urged Turkey, a candidate for EU membership, to avoid taking unilateral action in Iraq.
"It is crucial that Turkey continues to tackle this problem through cooperation between the relevant authorities," Commission spokeswoman Krisztina Nagy said in Brussels.
Iraqi prime minister Nuri al-Maliki telephoned Mr Erdogan to reiterate his commitment to combating the PKK.
Iraq's president, who is a Kurd, condemned the PKK tactics.
"We consider the activities of the PKK against the interests of the Kurdish people and against the interests of Turkey. We have asked the PKK to stop fighting and end military activity," President Jalal Talabani said during a visit to Paris.
Ankara blames the PKK, considered a terrorist organisation by the United States and the European Union, for the deaths of more than 30,000 people since the group launched its armed struggle for an ethnic homeland in southeast Turkey in 1984.