The U.S.-led occupation force in Iraq needs more international help to deal with security threats, including Al Qaeda terrorists, Iranian fighters and religious and ethnic squabbles, the top American commander in Iraq said Thursday.

"If a militia or an internal conflict of some nature were to erupt ... that would be a challenge out there that I do not have sufficient forces for," Lt. Gen. Ricardo Sanchez (search) said at a Baghdad news conference.

"There are security challenges that are looming in the future that will require additional forces, and those are issues that with the coalition, and with time, can be resolved."

Defense Secretary Donald Rumsfeld (search), who made an unannounced visit to Baghdad Thursday to meet with Sanchez and U.S. civilian Iraq administrator L. Paul Bremer (search), said the U.S. wants to move more quickly to bring former Iraqi soldiers into the country's new security forces.

The U.S. military is "looking at ways of accelerating" the process of bringing former members of Saddam Hussein's military — and possibly his security services — into the Iraqi security forces, according to the defense secretary.

"Foreign troops are not normal. They're temporary," he said. "Iraqi forces are normal. They are what ought to be."

Rumsfeld flew to Baghdad to see for himself how the American-led occupation of the country is progressing.

After stepping off a C-17 transport plane Thursday, Rumsfeld shook hands and posed for pictures with grinning Air Force service members on the tarmac. He then stepped over a traffic barrier and visited wounded soldiers in an air-conditioned hospital tent nearby.

One was Chief Warrant Officer 3 Robert Meyerhoff of ValleCrucis, N.C. Meyerhoff was wounded in the right leg Wednesday when his mail convoy was ambushed in Baghdad.

"I'm doing a lot better today than I was yesterday," Meyerhoff said after he shook Rumsfeld's hand.

The daily attacks on U.S. soldiers like the one that wounded Meyerhoff — as well as a rash of car bombings that killed more than 100 — have prompted some in Congress to call for more American troops to be sent to Iraq.

Rumsfeld said the top generals in Iraq don't want more than the 140,000 U.S. troops already on duty here. But, added, they do want more Iraqis working as police, soldiers, security guards and border patrols.

The United States formally disbanded the Iraqi military and the intelligence and security services that had supported Saddam Hussein's dictatorship.

Iraqi enlisted soldiers and junior officers from lieutenant colonel on down could be eligible to join the new Iraqi army, Rumsfeld said, adding that all will be carefully screened to weed out those with anti-American leanings.

Rumsfeld said that between 50,000 and 60,000 Iraqis are doing security work now, more than half of them working as police officers.

On the flight to Baghdad, Rumsfeld told reporters that there is a major mix of enemy fighters in Iraq from 10-20 different countries, such as Syria and Lebanon. Rumsfeld also said coalition officials are not seeing evidence that Iran and Syria have secured their borders to prevent the outflow of fighters to Iraq.

The defense secretary said the United States is working with allied countries surrounding Iraq — Saudi Arabia, Turkey, Kuwait and Jordan — to help stem the flow of foreign fighters streaming into Iraq. But he said that cooperation has been spotty so far.

The military is unsatisfied with the amount and quality of information they have about anti-American forces in Iraq, particularly about foreign fighters, Rumsfeld said.

"They're not comfortable at the moment with what they don't know," he said.

Saudi officials objected last month when U.S. officials suggested that many of the anti-American fighters in Iraq had crossed from Saudi Arabia, saying the Americans had left abandoned border posts on the Iraqi side of the remote desert frontier.

Many of the foreign fighters in Iraq are from Syria, with smaller numbers from Lebanon and other countries, Rumsfeld said.

The defense secretary said he hoped negotiations at the United Nations could result in a resolution that would encourage more countries to send troops to Iraq. Turkey, India and Pakistan have said they would send soldiers if there were U.N. authorization.

About 22,000 troops from more than two dozen other countries are part of the U.S.-led occupation force. The Americans on Wednesday formally turned over control of a sector of south-central Iraq to a division of troops led by Poland.

As U.S. diplomats pushed a new U.N. resolution aimed at persuading more nations to contribute troops, Russia gave its first signal that it could send peacekeepers to Iraq. Britain also said it was considering whether to increase its force levels.

British Defense Secretary Geoff Hoon (search) ordered a review of British troop levels following weeks of heightened insecurity. But Prime Minister Tony Blair said no decision had been made to send additional forces.

"We keep it under review constantly because we've got to get the job done, but there are no decisions that have been taken on additional troops," Blair said at a news conference.

Hoon's announcement was made after a published report that Foreign Secretary Jack Straw had proposed the deployment of 5,000 more British troops in Iraq. Britain has 11,000 troops in Iraq. Forty-nine British soldiers have died in the war, with 11 of them killed since May 1 when President Bush declared an end to major fighting.

Some nations are wary of sending troops to the region if the peacekeeping and military operations are still under U.S. control.

Germany and France on Thursday said the United Nations should have the responsibility for political process in Iraq.

German Chancellor Gerhard Schroeder told a news conference with French President Jacques Chirac in Dresden, Germany, that the two officials agreed that while they had opposed the U.S.-led war in Iraq, they wanted to help bring stability and democracy to the country now that the war was over.

"Such a perspective can only develop if the United Nations takes over responsibility for the political process and if an Iraqi administration is installed," Schroeder said.

On the military front, Sanchez said the coalition lacks sufficient troops to protect Iraq's porous borders or its thousands of miles of highways. Iraqi security forces are being trained to eventually patrol both.

But Sanchez maintained that no more U.S. troops are needed in Iraq. He said if a sudden conflict arose he would reassign forces to deal with it, but added the Army's existing missions could suffer as a result.

"I have communicated very clearly to Central Command, who in turn communicates to Washington ... and to senior leadership that has come through here, that I do not need additional U.S. forces," Sanchez said. "Clearly, I have also stated that if coalition forces were to be offered, we would gladly accept them."

In what could be a more immediate confrontation, Sanchez said U.S. troops would force the Badr Brigade, a Shiite Muslim militia, to disarm if reports of its reactivation prove true.

The Badr Brigade is the armed wing of the Supreme Council for the Islamic Revolution in Iraq. U.S. troops ordered the brigade disarmed and disbanded early in the occupation.

But on Wednesday, Abdel-Aziz al-Hakim — a member of the U.S.-picked Governing Council and brother of Ayatollah Mohammed Baqir al-Hakim, who was killed in last week's Najaf car bombing — suggested the militia had rearmed to provide security for Shiites.

On Wednesday, the United States asked the United Nations to take an expanded role in Iraq's security, political transition and reconstruction. The draft resolution would transform the U.S.-led military force in Iraq into a U.N.-authorized multinational force under a unified command.

Amid the rhetoric over troop levels, new fighting erupted Thursday in Iraq. U.S. forces exchanged fire with Iraqi guerrillas who lobbed at least six mortar rounds at them in intense fighting in downtown Tikrit.

The mortar shells missed their targets, causing no injuries or damage, said Lt. Col. Steve Russell. Russell commands the 4th Infantry Division's 1st Battalion, 22nd Regiment, which patrols Saddam Hussein's hometown of Tikrit, 120 miles north of Baghdad.

An American reconnaissance patrol, responding to the mortar attack, was ambushed with small-arms fire and rocket-propelled grenades on the eastern bank of the Tigris River, directly opposite the 4th Infantry's sprawling headquarters in one of the ousted leader's former palaces.

Bradley fighting vehicles were called in as reinforcements, opening fire on the guerrillas as tracer bullets lit the night sky over Tikrit, which was plunged into darkness. An intense firefight ensued and at least one house was on fire. Helicopters were heard hovering above.

Russell played down the attack, saying no U.S. casualties were reported, but one attacker might have been killed as the rest of the guerrillas disappeared.

"When you have such an incident, it appears to be a spike in activity. But in reality, it's a decline," Russell said.

Also Thursday, U.S. troops acting on a tip from an Iraqi raided a house in Tikrit and detained four people, including a suspected bomb maker. The troops seized weapons and ammunition and a box of explosives, wires, clocks, nails and other bomb-making material.

Col. James Hickey, commander of the 4th Infantry's 1st Brigade, said the man, who was not identified, surrendered without a fight. He is suspected of bomb-making activities in the Tikrit area and was being interrogated, Hickey said.

Fox News' Bret Baier and The Associated Press contributed to this report.