WASHINGTON: After months of debate, President Barack Obama will spell out a costly Afghanistan war expansion to a skeptical public Tuesday night, coupling an infusion of as many as 35,000 more troops with a vow that there will be no endless US commitment. His first orders have already been made: at least one group of Marines who will be in place by Christmas.

Obama has said that he prefers "not to hand off anything to the next president" and that his strategy will "put us on a path toward ending the war." But he doesn't plan to give any more exact timetable than that Tuesday night.

US President Barack Obama at the White House in Washington October 7, 2009.

The president will end his 92-day review of the war with a nationally broadcast address in which he will lay out his revamped strategy from the US Military Academy at West Point, NY. He spent part of Monday briefing foreign allies in a series of private meetings and phone calls.

Before Obama's call to Britain's Gordon Brown, the prime minister announced that 500 more UK troops would arrive in southern Afghanistan next month — making a British total of about 10,000 in the country. And French President Nicolas Sarkozy, whose nation has more than 3,000 in Afghanistan, said French troops would stay "as long as necessary" to stabilize the country.

Obama's war escalation includes sending 30,000 to 35,000 more American forces into Afghanistan in a graduated deployment over the next year, on top of the 71,000 already there. There also will be a fresh focus on training Afghan forces to take over the fight and allow the Americans to leave.

He also will deliver a deeper explanation of why he believes the US must continue to fight more than eight years after the war was started following the Sept. 11 attacks by al-Qaida terrorists based in Afghanistan. He will emphasize that Afghan security forces need more time, more schooling and more US combat backup to be up to the job on their own, and he will make tougher demands on the governments of Pakistan as well as Afghanistan.

"This is not an open-ended commitment," White House press secretary Robert Gibbs said. "We are there to partner with the Afghans, to train the Afghan national security forces, the army and the police so that they can provide security for their country and wage a battle against an unpopular insurgency."

On a few of the bigger questions most on the minds of increasingly restive members of Congress and the public, such as how much the additional $30 billion to $35 billion cost will balloon the already skyrocketed federal deficit, how long the US commitment will continue and how it will wind down, Obama was expected to make references without offering specifics.

Gibbs said detailed discussions on costs would be held later with lawmakers.

Even before explaining his decision, Obama told the military to begin executing the force increases. The commander in chief gave the deployment orders Sunday night, during an Oval Office meeting in which he told key military and White House advisers of his final decision.

At least one group of Marines is expected to deploy within two or three weeks of Obama's announcement and will be in Afghanistan by Christmas, military officials said. Larger deployments will begin early next year.

The initial infusion is a recognition by the administration that something tangible needs to happen quickly, officials said. The immediate addition of Marines will provide badly needed reinforcements for those fighting against Taliban gains in the southern Helmand province, and also could lend reassurance to both Afghans and a war-weary US public.

Obama's overall review was launched Aug. 31, when Army Gen. Stanley McChrystal, then the newly minted top US commander in Afghanistan, delivered to Pentagon brass his assessment of the situation on the ground and what was needed to turn it around. McChrystal produced a separate resource request, first seen by Obama on Oct. 1. The president's review was anchored by 10 extensive war council meetings, starting on Sept. 13, that featured a debate between a counterinsurgency strategy focused on protecting the local population and building up the Afghanistan government or a more limited counterterrorism strategy.

The final product is neither, though it leans more toward counterinsurgency.

The length of the process drew sharp barbs. Less than two months in, former Vice President Dick Cheney accused Obama of "dithering," beginning a drumbeat of criticism from Republicans. The White House shot back that the administration Cheney helped lead had given inordinate attention to Iraq while turning its back on Afghanistan.

But with US casualties in Afghanistan sharply increasing and little sign of progress, the war Obama once liked to call one "of necessity," not choice, has grown less popular with the public and within his own Democratic Party. In recent days, leading Democrats have talked of setting tough conditions on deeper US involvement, or even staging outright opposition.

The displeasure on both sides of the aisle is likely to be on display when congressional hearings on Obama's strategy get under way later in the week on Capitol Hill.

Obama spent much of Monday and Tuesday on the phone, outlining his plan — minus many specifics — for the leaders of France, Britain, Germany, Russia, China, India, Denmark, Poland and others. He also met in person at the White House with Australian Prime Minister Kevin Rudd.

A briefing for dozens of lawmakers was planned for Tuesday afternoon, just before Obama left for New York to give his speech against a military backdrop.

He also was to call Afghan President Hamid Karzai and Pakistan President Asif Ali Zardari — two leaders on whom the success of the plan will depend heavily.

In Afghanistan, rampant government corruption and inefficiency have made US success much harder. Obama was expected to place tough conditions on Karzai's government, along with endorsing a stepped-up training program for the Afghan armed forces in line with recommendations this fall by US trainers.

That schedule would expand the Afghan army to 134,000 troops by next fall, three years earlier than once envisioned.

The president faces a trickier task in talking tough on Pakistan.

Though extremist fighters and al-Qaida leaders are believed to be based in its western region near the border with Afghanistan, public scoldings from Washington can hurt as well as help Pakistani efforts because of pervasive anti-American sentiment. The US cannot send troops into Pakistan, and rarely discusses the anti-terrorist missile strikes conducted inside Pakistan from US drones.

Military officials said the speech is expected to include several references to Iraq, where the United States still has more than 100,000 troops. The strain of maintaining that overseas war machine has stretched the Army and Marine Corps and limited Obama's options.

He is expected to at least implicitly pledge not to return to the worst days of the Iraq war, when the Army was resorted to 15-month tours with little time at home between deployments and when National Guard and reserve troops were subjected to lengthy tours.