US Defence Secretary Mr Donald Rumsfeld has arrived in Baghdad on a surprise unannounced visit.
He is in the Gulf region for a fact-finding mission as his government continues efforts tried to get more nations to contribute troops and cash for peacekeeping in Iraq.
Mr Rumsfeld said more US forces were not needed but called for more Iraqi and international involvement in security.
But in a reminder of the dangers in Iraq, US troops fought Iraqi guerrillas who fired mortars near their base, then raided homes to detain suspected bomb-makers in a night of drama around Saddam Hussein's hometown of Tikrit. Iraqis then fired rocket-propelled grenades on a patrol.
There were no American casualties, but US commanders said at least one Iraqi may have died in the fighting witnessed by a Reuters crew accompanying the military.
In another overnight incident near Baquba, 30 miles northeast of Baghdad, US troops ambushed and killed three Iraqi guerrillas laying explosive devices on a roadside.
In New York, the United States faced a sceptical UN Security Council on a resolution crafted to induce more nations to send troops and money to support the US-led occupation.
While Washington has made some concessions, diplomats said the United States faced intense talks as France and other Security Council members were wary of rubber-stamping the US occupation. The measure wants UN endorsement of the US-selected Iraqi Governing Council as an interim government.