Defense Secretary Robert Gates said on Friday he did not expect America's NATO allies to provide many more troops for the war in Afghanistan, Reuters reported.
Gates said the United States would try to send three more brigades -- likely more than 10,000 troops once support forces are included -- to Afghanistan next year, on top of existing commitments.
But he said the longer-term solution was to hand the fight to Afghan forces and it would be a "terrible mistake" if the conflict in Afghanistan was seen as America's war.
"My personal view is that we are not likely to get significantly larger numbers of troops from our allies and partners," he said.
Rising insurgent violence -- now at its highest level since U.S.-led forces toppled the Taliban in 2001 -- is causing widespread alarm in Afghanistan and in Western capitals.
Both candidates in Tuesday's U.S. presidential election, Democrat Barack Obama and Republican John McCain, have pledged to send more troops to Afghanistan.
Since taking over at the Pentagon in December 2006, Gates has spent much of his tenure trying to persuade allies to send more troops and equipment to Afghanistan, with limited success.
His comments, as the Bush administration nears its end, seemed to be an admission from Gates that he believes he has pushed that effort as far as he can.
Gates made his comments to reporters as he flew back to Washington from a ceremony in Tampa, Florida, to install U.S. Army Gen. David Petraeus as head of U.S. Central Command, which oversees the wars in both Afghanistan and Iraq.
The United States has about 32,000 troops in Afghanistan. Some 13,000 of them serve in the 50,000-strong NATO-led force charged with helping to stabilize the country.
"We will be making a terrible mistake if this ends up being called America's war. This is the Afghans' war for their own country and we're there to help them," Gates said.
"What I would like to see -- and I think what everybody would like to see -- is the most rapid possible further expansion of the Afghan military forces because this needs to be an Afghan war, not an American war and not a NATO war."
The United States has backed plans to double the size of the Afghan army to 134,000 soldiers over five years.
"It may well not stop there," Gates said.
He said that while no higher target for the size of the Afghan Army had been discussed, the number of people employed in the security sector in Afghanistan was far lower than in Iraq.