MANAMA, Bahrain —Defense Secretary Robert Gates sees a rationale for sending more troops to Afghanistan, but the question is how much more can be contributed at a time when President Bush is ramping up U.S. firepower in Iraq and the Persian Gulf.

Gates said that he wants to ensure that gains made against extremism in Afghanistan since the U.S. invaded to topple the Taliban regime in October 2001 are not lost as the Taliban re-emerges.

"I think it is important that we not let this success here in Afghanistan slip away from us and that we keep the initiative," he told reporters at Bagram Air Base, the main U.S. military air hub in Afghanistan. "There's no reason to sit back and let the Taliban regroup."

Gates said that commanders in Afghanistan had recommended a troop increase, and he suggested he was inclined to urge Bush to go ahead with it. He mentioned no numbers during the talk with reporters on Wednesday, but a senior official traveling with Gates said it would not be anything close to the 21,500 extra troops Bush is sending to Iraq. The official, who spoke on condition of anonymity, said it likely it would be one or two battalions — no more than a couple of thousand troops.

On Wednesday evening, Gates flew to Saudi Arabia, where he met for more than two hours with King Abdullah and Crown Prince Sultan, who is the kingdom's defense minister, and other top officials.

Gates reassured the Saudis that Bush intends to stick to his strategy of building a democracy in Iraq, where Iranian Shiite influence is a major concern for the Saudis, according to a senior official who attended the talks and briefed reporters later after the U.S. delegation finished its day by flying to Bahrain.

Gates also made a pitch for more Saudi help in Iraq, including economic assistance, but he made no specific requests, the official said, speaking on condition of anonymity.