Fighting has intensified in northern Iraq, where U.S.-led coalition forces have bombed Iraqi army positions near key oil centers. Because there are various groups and countries with strong interests in the region, some analysts say the conflict in northern Iraq could become a "war within a war."

In their first bombing raids in northern Iraq, American and British coalition planes struck Iraqi front-line positions and military barracks near the strategically important cities of Mosul and Kirkuk -- two key oil centers. Meanwhile, hundreds of American troops have been flown to the region to join other special forces and intelligence teams which have been working with Kurdish opposition forces in northern Iraq since last year. The original plan was for U.S. troops to cross overland into northern Iraq from Turkey, but when Turkey refused access, the coalition's strategy changed. Instead, troops are being flown to airfields under the control of the Patriotic Union of Kurdistan and the Democratic Party of Kurdistan.

The 70,000 strong Kurdish army is eager to join the U.S. and British coalition forces in battling the Iraqi army. Kurdish forces have already been helping the coalition against Islamic extremists in the Ansar Al-Islam area in far eastern Iraq.

The situation in northern Iraq could become more complicated if Turkey follows through on its stated ambition to increase the number of its troops inside northern Iraq. "The Kurdish leadership has made it very clear that if Turkey came across the border that there would be conflict between Kurdish pesh mergas [guerrilla fighters] and those Turkish forces," says David Phillips, deputy director of the Center for Preventive Action at the Council on Foreign Relations, has worked extensively in Northern Iraq. "It is in no one's interests for Turkey to transgress Iraq's territorial integrity and try to position additional troops in Iraq Kurdistan."

U.S. officials in Ankara have been trying to convince Turkish officials they do not need to position extra troops inside Iraq. President Bush repeated that position over the weekend. "We're in constant touch with the Turkish military as well as Turkish politicians. They know our policy, and it's a firm policy," he says. "And we've made it very clear to them we expect them not to go into northern Iraq, and they know we're working with the Kurds to make sure there's not an incident that would cause there to be an excuse to go into northern Iraq."

Turkey has had a few thousand troops in northern Iraq since the late 1990s but says a larger presence is necessary to prevent instability caused by the war and avert Kurdish refugee flows into Turkey. It has massed its forces along its southern border with Iraq.

A former U.S. diplomat in Iraq, Joseph Wilson, says it is important to keep the Turks and Kurds from fighting each other. Ambassador Wilson says a smaller "war within the war" (for greater Iraq) could break out if Turkish and Kurdish forces clashed for control of Kirkuk -- the capital of the northern oil producing region. "That was, I think, the most important reason for us to have wanted to be able to deploy troops from the north, which was basically to ensure that Kirkuk remained in the hands of the United States essentially and didn't fall prey to this sort of fighting between Turks and Kurds," says Mr. Wilson.

David Phillips agrees, and adds that Kirkuk is a flashpoint for disputes among Iraqis. "Many hundreds of thousands of Kurds - I believe the number is 300,000 - have been evicted over the years from Kirkuk. Also as a part of Saddam's Arabization programs, many Iraqi Turkomen have been evicted. There have been Arabs that have been moved into Kirkuk," he said. "It's very important that -- in the process of the spontaneous return of displaced persons -- that there be orderly management of their return so that there is no revenge --taking or vigilantism that might cause violence in Kirkuk that would spiral out of control."

Mr. Phillips says Turkey could point to that kind of violence as a justification for projecting its forces deep into Iraq.

Robert Olson, a professor of Middle East and Islamic History at the University of Kentucky, says if U.S. forces use Kurdish fighters in their fight to control Kirkuk, that will likely prompt Turkey to send in its troops. "And I think the United States is going to use the Kurdish forces for this, which very much strengthens the Kurdish position," he says. "But it does enhance the possibility, and I think there's a real possibility, there will be substantial armed conflict between the Kurds and the Turks."

Once coalition forces stabilize Kirkuk, they are still expected to face difficulties just to the south -- on the way to Baghdad -- at the city of Tikrit. Tikrit, Mr. Phillips points out, is the homeland of Saddam Hussein. "It is a Sunni Arab stronghold. Because of the deep involvement of Tikritis in atrocities committed by the regime, many Tikritis know they have no future in a democratic Iraq," he says. "They're likely to hold out fiercely there."

Mr. Phillips says he expects there will be considerable fighting to achieve the liberation of Tikrit.