Top Pentagon leaders are expected soon to recommend to Defense Secretary Robert Gates which additional U.S. troops could be sent to Afghanistan over the next month or so, according to a senior military official.

The units are likely to be small and could include engineers, ordnance disposal troops and other support forces needed to shore up fighting needs and the training of Afghan forces. Officials have not ruled out identifying a larger, brigade-sized unit before the end of the year that could either be shifted to Afghanistan from a planned deployment to Iraq or moved from some other location.

U.S. commanders in Afghanistan have been asking for three combat brigades, or roughly 10,000 more troops, to help quash rising violence there.

The senior official, who requested anonymity because the proposals are not public, said the recommendations have not yet been approved by Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, or delivered to Gates.

Last week Gates said he is hoping to address some of those requirements sooner rather than later.

On Wednesday, Pentagon press secretary Geoff Morrell said that any sizable increase in troop levels in Afghanistan may not come until the new administration takes over next year.

Any decision to shift large units such as combat brigades into Afghanistan after they've been preparing to go to Iraq later this year would take additional training and time, Morrell said.

"You can't snap your fingers and make this happen, unfortunately," he said. He added later that the Pentagon is not kicking any decisions down the road to the next White House. Rather, he said, decisions made now may require months to execute.

While he stressed that no decisions have been made yet, the issue was likely among those discussed when President Bush met with the Joint Chiefs of Staff on Wednesday in a classified briefing at the Pentagon.

Bush has made the Iraq war, now in its sixth year, the Defense Department's top priority, and defense officials have been candid about the fact that the focus on Iraq has meant fewer troops and other military assets available for the campaign in Afghanistan.

"That is the war which we have focused on," Morrell said of Iraq, asserting, "That is the war we are now winning."

Officials have said that if improved security conditions in Iraq hold, they hope to be able to devote more troops to Afghanistan, where the Taliban is resurgent following its ouster by a U.S.-led invasion in late 2001.

Iraq's ambassador to the U.S. said Wednesday that Al Qaeda's foreign fighters who have for years bedeviled Iraq are increasingly going to Afghanistan to fight instead.

"We have heard reports recently that many of the foreign fighters that were in Iraq have left, either back to their homeland or going to fight in Afghanistan. Afghanistan is now seeming to be more suitable for Al Qaeda fighters," Ambassador Samir Sumaida'ie said.

Al Qaeda had training camps and a headquarters in Afghanistan, under the protection of the then-ruling Taliban, until the U.S. invasion after the Sept. 11 terroist attacks on New York and Washington. With Al Qaeda forced out of Afghanistan, the U.S. invasion of Iraq in 2003 quickly drew outside fighters there.

Sumaida'ie said Al Qaeda is finding it now increasingly difficult to operate in Iraq, beginning with the rebellion of the largely Sunni tribes in Anbar Province in 2006 and 2007. Until then, Al Qaeda had ruled by intimidation and violence, establishing physical control and setting up a shadow government in large swaths of Iraqi territory.

Sumaida'ie's comments echoed those of the top U.S. military commander in Iraq. Gen. David Petraeus told The Associated Press last week that Al Qaeda appears to be reassessing its chances of success in Iraq.

A U.S. counterterrorism official who spoke on condition of anonymity to discuss intelligence reporting said foreign fighters are generally not leaving Iraq for Afghanistan, but new recruits to Al Qaeda are being sent to Afghanistan and Pakistan instead of Iraq. The numbers in all countries are small, however. The vast majority of Al Qaeda in Iraq are native born, and extremists in Afghanistan and Pakistan are overwhelmingly Pashtun fighters from the region.