President George W. Bush, facing Turkish threats of a military incursion into Iraq to root out Kurdish rebels, will assure Turkey's prime minister on Monday he is committed to helping to combat the militants.

Turkish Prime Minister Tayyip Erdogan, who will meet with Bush at the White House, has made clear that he wants concrete action to counter the Kurdish rebels who have been launching attacks on Turkey from Iraqi soil.

If Erdogan walks away from the meeting dissatisfied, there could be major repercussions for Bush's effort to stabilize Iraq where he has lately been touting progress.

Turkey, a NATO member with the alliance's second-biggest army, has sent up to 100,000 troops to the Iraqi border, backed by tanks, artillery and aircraft.

Ankara has said it may take cross-border action soon. The White House, fearing such action could destabilize the wider region, has been urging Turkey to refrain from a major operation in an area of Iraq that has so far escaped the violence plaguing other parts of the country.

Turkish officials have portrayed the meeting between Bush and Erdogan as a last chance effort to avert a military strike.

Bush is going to have to offer something, said Bulent Aliriza, an expert on Turkey at the Center for Strategic and International Studies in Washington. This is an unusual situation. Most of the time, these meetings are very carefully choreographed ahead of time.

But Aliriza said an attempt by U.S. Secretary of State Condoleezza Rice to lay the groundwork for the meeting during a weekend trip to Istanbul appeared to do little to satisfy Ankara's demands for concrete steps.

Visiting Turkey for a conference on Iraqi security this weekend, Rice called the PKK militants a common enemy but did not spell out what Washington might do to stop from them using Iraq as a base for attacks on Turkey, where they seek an independent Kurdish state.

The conference on Iraq in Istanbul also brought a vow from the Iraqi government to hunt down PKK militants responsible for raids into Turkey.

Erdogan has come under pressure to act in northern Iraq after dozens of Turkish soldiers were killed in PKK attacks in recent weeks. During an attack on a Turkish army post near the Iraqi border last month, PKK guerrillas killed at least 12 soldiers and captured eight.

The eight soldiers were freed on Sunday, which could give a boost to the talks between Bush and Erdogan.

Asked last week to preview the meeting, Bush gave few specifics, saying only that they would discuss how we can work together to prevent people from coming out of mountain ranges to do harm to Turkish troops. And we will have a good, substantive discussion, as you would expect allies to do.

George W. Bush Iraq