WASHINGTON/KABUL - President Barack Obama plans to announce on Tuesday that he will send about 30,000 more U.S. troops to Afghanistan in a long-awaited war strategy shift that he hopes will defeat the Taliban and allow for a U.S. exit.

After three months of deliberations that some critics called dithering, Obama is to lay out his plan in a speech to cadets at the U.S. Military Academy at West Point, New York.

The high-stakes televised address will take place at 8 p.m. local (0100 GMT Wednesday). The White House says he has already given orders for the troops increase to his commanders.

Before the speech, Obama spoke for an hour by video phone to Afghan President Hamid Karzai, Karzai's office said.

Washington has had a fraught relationship with Karzai since Obama took office, which worsened over the past three months because of a fraud-tainted Afghan presidential election.

The troop increase represents a major gamble by Obama. He came to office vowing a greater focus on Afghanistan but has faced skepticism from some key advisers about the wisdom of putting more American lives and money on the line for a government in Kabul widely seen as corrupt and inept.

Obama plans to stress in his speech that the United States does not have an open-ended commitment in Afghanistan, but rather wants to hand over power to freshly trained Afghan forces and start withdrawing as soon as is practicable.

His challenge is to reverse what U.S. military commanders call a deteriorating situation due to a resurgent Taliban.

He also aims to persuade Karzai, who is due to name his new cabinet in coming days, to crack down on corruption and improve governance in return for U.S. support.

Both sides played down their differences at the Afghan leader's inauguration last month, Karzai vowing to fight graft and U.S. Secretary of State Hillary Clinton praising his steps.

Obama is also expected to stress the need for Pakistan to do more to fight militants who have crossed into Afghanistan. The administration has said getting the policy right in Islamabad is just as important as in Kabul.

U.S. officials said Obama would announce he has authorized sending about 30,000 more troops to Afghanistan. Currently there are roughly 68,000 U.S. troops and 42,000 allied forces there.

Obama is not expected to set a specific pullout date. The strategy envisages a phased troop buildup over the next 12 to 18 months followed by a gradual drawdown and handover to Afghan forces over three to five years, officials said.

A TOUGH SELL

The president may face a tough sell at home with many Americans weary of the war begun after the September 11 attacks in 2001 and wanting more focus on the weak U.S. economy.

James Monaghan of Watertown, New York, reflected this mood in talking about his 20-year-old daughter based at nearby Fort Drum and currently deployed in Iraq.
She's got kids. She's got a husband ... in the military as well, he said. It's time for family to come home. Bring the kids home. You know, bring the kids home, he said.

Many Afghans, too, are wary. In Kandahar, the southern city where the largest share of reinforcement are likely to be sent, money changer Agha Lala said new troops would only bring more suicide attacks and roadside bombs and loss of civilian lives.

Obama's announcement could set off a battle in congress over funding, since his own majority Democrats oppose a big troop surge. The added cost could reach $20-40 billion. Some Democrats have talked of imposing a war surtax to pay for it.

The new strategy will emphasize securing Afghan population centers and accelerating the training of Afghan security forces to gradually assume control.

Pentagon officials hope other NATO members will supplement the U.S. surge with up to 10,000 more troops, pushing the total number of reinforcements close to the 40,000 sought by the U.S. and NATO commander in Afghanistan, General Stanley McChrystal.

Britain has said it expects countries to pledge only a further 5,000 troops. The president on Monday talked to the leaders of Britain, France, Russia, Denmark and others.

British Foreign Secretary David Miliband said Obama would make clear the withdrawal of U.S. troops would depend on building up Afghan forces to defend themselves.

...their ability to prevent Afghanistan becoming a badland for al Qaida is very important indeed, Miliband told BBC radio.

The U.N. special envoy to Afghanistan, Kai Eide, said there must be more to the new strategy besides just sending reinforcements.

The increase in troop level has to be accompanied by a continued effort on avoiding civilian casualties, respecting cultural ... sensitivities of the Afghan people, these two have to go hand in hand for this to succeed, he said in Kabul.

(Additional reporting by Patricia Zengerle, Phil Stewart, Adam Entous and Sue Pleming in WASHINGTON; Katharine Jackson in WATERTOWN; Ismail Sameem in KANDAHAR and Stefano Ambrogi in LONDON)