Unremitting assaults on US-led occupation forces and a spate of recent bomb attacks are likely to be on Rumsfeld's agenda when he meets senior military leaders in the region.
Speaking to reporters on his plane on Thursday, he said more American forces were not needed in the country, but called for more Iraqi and international involvement in security.
"I haven't been back into Iraq or Afghanistan I guess since last ... April or May and it seemed to me that it was important to have an opportunity to get a first hand sense of how things are going," he said.
Around 20,000 to 22,000 non-US soldiers are deployed in Iraq and Rumsfeld said he would like that number to go up by another division - about 15,000 soldiers.
He also said efforts should be made to bolster the size of the Iraqi security forces.
But in a reminder of the daily dangers in Iraq, US troops have fought Iraqi resistance fighters in Saddam Hussein's hometown of Tikrit.
They then raided homes to detain suspected bomb-makers before Iraqis fired rocket-propelled grenades at a patrol.
US soldiers are unable to maintain
security in Iraq
There were no American casualties, but US commanders said at least one Iraqi may have died in the fighting.
In another overnight incident near Baquba, 50 km northeast of Baghdad, US troops ambushed and killed three Iraqi resistance fighters laying explosive devices on a roadside, the US military said.
Meanwhile, in New York the US 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 America faced intense negotiations as France and other Security Council members were wary of rubber-stamping the occupation.
The resolution wants UN endorsement of the US-selected Iraqi Governing Council as an interim government.