Secretary of Defense Robert Gates, on his second trip to Iraq in less than a month, arrived unannounced Friday in this southern city to consult with British and other allied commanders.

Britain, which has the largest troop contingent among the U.S. allies, with about 7,000 soldiers in the Basra area, is planning to withdraw a large portion of them this year.

Gates said at the outset of his weeklong overseas trip that he realized the security situation in southern Iraq is different than in Baghdad, where the United States is building up its troop strength.

Gates was meeting with Gen. George Casey, the top U.S. commander in Iraq, as well as Maj. Gen. Jonathan Shaw, the newly arrived commander of British forces here. Later Gates was to meet with commanders from Poland, Australia, Denmark and Romania, and have lunch with coalition troops who are training the Iraqi army.

On his first visit to Iraq after being sworn in on Dec. 18, Gates met in Baghdad with U.S. commanders and Iraqi government leaders just weeks before President Bush announced his new strategy for Iraq, which includes sending an additional 21,500 troops to Baghdad and the western Anbar province.

After meeting earlier with the leaders of Saudi Arabia and Qatar, Gates said Thursday that those two key U.S. allies in the Persian Gulf remained skeptical of the Iraqi government and are not fully convinced Bush's plan for stabilizing Baghdad will succeed.

Gates told reporters both want the United States to succeed in Iraq. But asked whether they expressed full confidence in the Bush plan for quelling sectarian violence in Baghdad, the Pentagon chief replied, "I would say that they expressed hope."

"I think they're both concerned about the situation in the country and the level of violence," he said.

Gates met with the Emir of Qatar, Sheikh Hamad bin Khalifa al-Thani, at a palace in Qatar; on Wednesday night he met with King Abdullah of Saudi Arabia at a royal hunting lodge out of Riyadh, the capital.

"What I took from their comments was clearly concern about whether the government of Prime Minister (Nouri al-) Maliki can actually deliver on its commitments — quite frankly, these are reservations that have been expressed in Washington, and we will be watching," he told reporters after flying to Manama, Bahrain.

Gates' overseas tour began in London and took him to NATO headquarters in Brussels, Belgium, and to Afghanistan before he arrived in the Gulf on Wednesday.

Gates also told reporters Thursday that the Iranians are "overplaying their hand" on the world stage in a belief that setbacks in Iraq have weakened the United States. He said he told the Saudi and Qatari leaders he believes the Iranians "believe they have the United States at some disadvantage because of the situation in Iraq."

Many of the Gulf nations are worried about a rising Iranian influence in their region — a concern made more acute by the prospect for a further slide toward civil war in Iraq and its uncertain consequences for the United States.

With regard to U.S. failure thus far to achieve stability in Iraq, Gates said, "I think that our difficulties have given them (the Iranians) a tactical opportunity in the short term, but the United States is a very powerful country." Asked about the prospects for military conflict with Iran, whose nuclear program is seen by the Bush administration as a growing threat to U.S. interests, Gates said, "There are many courses of action available that do not involve an open conflict with Iran — there's no need for that."

Gates said that although he had publicly advocated negotiating with Iran as recently as 2004, he now advises against that.

"Right at this moment, there's really nothing the Iranians want from us," he said. "And so, in any negotiation right now we would be the supplicant," asking Iran to stop doing such things as enriching uranium for its nuclear program.

"We need some leverage, it seems to me, before we engage with the Iranians," he added. "And I think at some point engagement probably makes sense."

On his second overseas trip since replacing Donald H. Rumsfeld as Pentagon chief, Gates visited the headquarters of Central Command's naval staff, which is located here with the U.S. Navy's 5th Fleet.

Then he flew to Qatar to meet with the emir. Afterward he visited an air base from which Central Command's air staff plans, runs and monitors air operations throughout the Middle East and Central Asia. Under ground rules imposed by U.S. officials, reporters traveling with Gates were prohibited from identifying the base or the country in which it is located.

Gates also met at the base with Gen. John Abizaid, the head of Central Command, whose forward headquarters is in Qatar. Abizaid is due to retire in March; Navy Adm. William Fallon has been nominated to replace him.