BAGHDAD, Iraq — New Defence Secretary Robert Gates, in an unannounced trip to the battlefront, discussed a possible infusion of more US troops into Iraq with American commanders yesterday but said no decisions have been made.On just his third day in his post, Gates journeyed to Iraq armed with a mandate from President Bush to help forge a new Iraq war strategy. His goal is get advice from his top military commanders on a new strategy for the increasingly unpopular, costly and chaotic war — a conflict that Bush conceded Tuesday the US is not winning.

“We discussed the obvious things,” Gates told reporters after meeting with top US generals. “We discussed the possibility of a surge and the potential for what it might accomplish.”

His trip so soon after taking office underscored the Bush administration’s effort to be seen as energetically seeking a new path in the conflict.

Gates said he was only beginning the process of determining how to reshape US policy in the war. He said before making final decisions, he would also confer with top Iraqi officials about what the future American role in the country should be.

In Washington, Bush acknowledged he is considering sending more troops to Iraq but said he had yet to make up his mind.

“I will tell you we’re looking at all options. And one of those options, of course, is increasing more troops,” Bush said.

Bush also said he is ready to boost the overall size of the US military, following recent complaints by top generals that the forces have been stretched too thin by the worldwide campaign against terrorists. He used no figures, but said he was asking Gates to produce a plan for the expansion.

Gates said he was just starting to study that idea, but said he was concerned about the military’s potential ability to deploy if needed for possible confrontations with North Korea and Iran and to respond to catastrophic natural disasters.

Gates spoke to reporters after meeting with commanders, including Army Gen. John Abizaid, commander of US forces in the Middle East; Gen. George Casey, the top commander in Iraq; and Army Lt. Gen. Ray Odierno, in charge of day-to-day operations in Iraq.

Abizaid and Casey have both raised questions in the past about the value of sending thousands of extra troops into Iraq, where violence has been rising in recent months.

Several top US commanders have been wary of even a short-term troop increase, saying it might only bring a temporary respite to the violence while confronting the US with shortages of fresh troops in the future.

Asked at a news briefing about a possible surge of US troops, Casey repeated his concern that additional troops have to be for a particular reason.

“I’m not necessarily opposed to the idea, but what I want to see happen is when, if we do bring more American troops here, they help us progress to our strategic objectives,” Casey said.

“All options are on the table,” said Abizaid.

Gates and the generals did not cite any figures or timetables for a possible troop increase.

Among the proposals Bush is considering is buttressing the 140,000 US troops currently in Iraq to try to control surging violence in Baghdad and the unabated Sunni insurgency in Anbar province. Extra forces would also make it easier for the US to increase the number of American advisers for Iraqi security forces.

Shortly before Gates’ arrival, the US military in Iraq announced that a senior al-Qaida leader had been arrested in Mosul on December 14 and that security responsibilities in Iraq’s southern Najaf province were handed over to Iraqi forces earlier yesterday. It was not clear whether the announcements were timed to coincide with Gates’ visit.

Gates’ trip to Iraq comes with the Bush administration under intense pressure from Congress and the American public to sort through options for a war that has caused the deaths of more than 2,940 US troops and cost more than $300 billion. More than three-and-a-half years after the US invasion that toppled Saddam Hussein, the conflict now involves insurgents and bloodshed between Sunnis and Shiites that seems on the cusp of civil war.

Bush is considering choices ranging from a short-term surge of thousands of troops to bring the escalating violence in Baghdad and Anbar province under control, to removing combat US forces and accelerating the training and equipping of Iraqi security forces. More than one-third of the US troops in Iraq are combat forces.

Gates went to Iraq earlier this year as a member of the Iraq Study Group, a bipartisan commission that spent nine months assessing the situation in Iraq. It produced recommendations that include phasing out most US combat troops by early 2008, increasing military training for Iraqis and including Iran and Syria in regional efforts to end the violence.

Rumsfeld resigned last month after Democrats swept elections to win control of the House and Senate next year. Their triumph was powered by an American electorate that many believe have lost patience with the conflict.