WASHINGTON - President Barack Obama faces a decision later this year whether to send an extra 10,000 US troops to Afghanistan, amid an escalating war against Islamist insurgents, defense officials said.
A top general and senior Pentagon official disclosed on Wednesday for the first time details of a pending request from the US commander in Afghanistan for yet more troops for a war that has already lasted more than seven years.
"What the president was told is that the request (for more troops) is out there, but he doesn't have to make a decision until the fall so that the troops would arrive as planned in 2010," Michele Flournoy, undersecretary of defense for policy, told the Senate Armed Services Committee.
The US commander in Afghanistan, General David McKiernan, would "reassess" his request later in the year, she added.
General David Petraeus, the US Central Command chief, said he had approved the troop request but that the Defense Department had not yet formally passed it on to the White House.
The 38,000-strong US contingent in Afghanistan is due to expand to about 68,000 troops by the end of the year, Flournoy said. About 32,000 other foreign allied forces are also deployed there under NATO authority.
But legislators sought clear benchmarks to measure the progress of the US mission in the country.
"How will we know if we're winning?" asked Senator Susan Collins of Maine.
Obama has weighed competing advice in his administration on troop levels, with McKiernan requesting more boots on the ground while others -- including reportedly Vice President Joe Biden -- voicing caution about an open-ended commitment.
Defense officials had previously said McKiernan requested about 30,000 additional troops -- roughly doubling the size of the US force -- and that recent decisions by Obama had met his requests for 2009.
Former presidential candidate John McCain and other Republican lawmakers have accused Obama of failing to provide all the troops the US commander had requested.
Although he praised Obama's new strategy, McCain warned at the hearing of possible "incrementalism," saying the new administration appeared to be delaying decisions on troops or goals for Afghan security forces.
McCain said that "to dribble out these decisions, I think, can create the impression of incrementalism."
Obama was also facing growing criticism on the political left over expanding US military presence in Afghanistan.
"How are we going to know when our national task is finished?" asked Senator Jim Webb of Virginia, a Democrat, at the hearing. "What is the end point?"
Both Flournoy and Petraeus said US military operations aimed to eventually shift security duties to Afghan forces.
Describing the challenges of the Afghanistan mission, Petraeus warned the war would require "a sustained substantial commitment."
"There will be nothing easy about the way ahead in Afghanistan and Pakistan," the general said.
Petraeus, credited as the mastermind behind a successful counter-insurgency campaign in Iraq, acknowledged that more forces were needed in Afghanistan according to troop numbers prescribed in an irregular warfare manual he helped author.
US troops must "be seen as good guests and partners, not as would-be conquerors or superiors" who try to avoid civilian casualties, he warned.
The general also said Pakistan's role was crucial in stemming the threat from Taliban and Al-Qaeda-linked insurgents operating on the country's porous border with Afghanistan.
He said the Islamist militants posed an "existential threat" to Pakistan itself, echoing words Obama has used as the administration steps up pressure on Islamabad to crack down on the insurgents.
Since taking office, Obama has approved an additional 21,000 troops for the Afghan war, including a 4,000-strong brigade that will focus on training Afghan security forces.
And in the last months of his term, former president George W. Bush approved the deployment of reinforcements, including an additional combat brigade for Afghanistan.
During his election campaign, Obama vowed to send more combat troops to Afghanistan and to make the war a top priority, charging his predecessor had neglected the mission because of his focus on Iraq after the US-led invasion there in 2003.