The strategy will blend a broad-based counterinsurgency with hunt-and-kill counterterrorism tactics.
Washington hopes the buildup will create conditions to allow a U.S. troop drawdown and handover to Afghan forces over a three- to five-year period, military officials said.
Obama was not expected to announce a specific pullout date when he outlines his strategy in an address to the American people on Tuesday night from the U.S. Military Academy at West Point, New York, officials said.
MIX OF COUNTERINSURGENCY, COUNTERTERORRISM
Obama will continue the existing counterinsurgency strategy with a greater focus on protecting major Afghan population centers along with agricultural areas and transportation routes, officials said.
This will be combined with a counterterrorism campaign, advocated by Vice President Joe Biden, using unmanned aerial drones and special operations forces to combat Taliban and al Qaeda fighters along the Afghanistan-Pakistan border and possibly in Afghanistan's more sparsely populated areas.
TOP PRIORITY IS TRAINING AFGHANS
The White House said a top priority for Obama will be accelerating the training of Afghan security forces to take over responsibility from U.S. and NATO troops.
One leading proposal would set the goal of having about 400,000 Afghan army troops and national police officers, more than twice the current number, by 2012, a year earlier than planned.
But several key administration officials doubt that the accelerated timetable and 400,000-man goal can be achieved.
OBAMA TO STRESS HANDOVER TIMEFRAME
U.S. officials said a transition to greater Afghan control could begin quickly in parts of Afghanistan that are more stable. Britain has called for the transfer of at least five Afghan provinces to lead Afghan control by the end of 2010 but it is unclear what that would entail.
General Stanley McChrystal, the top U.S. and NATO commander in Afghanistan, has told lawmakers that a troop drawdown could begin by 2013.
Defense Secretary Robert Gates said the U.S. withdrawal plan in Iraq was a possible model -- U.S. troops would pull back and eventually out of city centers as Afghan forces assume the leading role.
The White House has said it sees U.S. forces out of the country by 2017-2018.
TROOP INCREASEThe 30,000 troop increase falls short of the 40,000 recommended by McChrystal to counter a resurgent Taliban.
But NATO member-states and other allies are expected to pledge a further 5,000 troops on top of those sent by the United States.
Currently, there are about 68,000 U.S. troops and 42,000 allied forces in Afghanistan.
Obama rejected options favored by Biden and some of his domestic policy advisers to deploy between 10,000 and 20,000 troops.
ACCELERATED DEPLOYMENT SCHEDULE
The Pentagon had initially envisaged carrying out the troop buildup in Afghanistan gradually, over 12-18 months, giving Obama the option of changing course before all of the new troops are in place.
But in a last minute shift, administration officials said the 30,000 troops would arrive within six months.
Leading the U.S. buildup will be a 9,000-plus Marine Expeditionary Brigade augmented by aviation support units.
The Army will send four brigades, three on combat missions and one to train Afghan forces. Army brigades are typically made up of about 4,000 soldiers each.
Commanders want the Marines concentrated in Taliban strongholds in southern Afghanistan, including Kandahar and Helmand, the group's opium-producing heartland.
U.S. Army reinforcements are expected to be sent to eastern Afghanistan near the border with Pakistan.
A key part of Obama's strategy will be benchmarks for President Hamid Karzai's government to crack down on corruption and improve governance. U.S. officials say getting Karzai to do so is critical to a successful counterinsurgency that hinges on Afghans supporting their government instead of the Taliban.
Gates sees no quick fix to those problems and top officials said the United States could withhold aid contracts to pressure Karzai's government to act.
DIVIDE AND CONQUER
Administration officials say Obama wants greater outreach to groups that fight alongside the Taliban but could be persuaded to lay down their weapons in exchange for a greater role in local governance and Western-funded development.As part of the revised strategy, the United States wants to see a crackdown on Taliban insurgent leaders based in Pakistan, including Mullah Omar and an allied network headed by veteran commander Jalaluddin Haqqani. Islamabad has been reluctant to act against them, say U.S. officials, citing suspected links between the militants and elements of Pakistani intelligence.
PAYING THE BILLS
The White House Office of Management and Budget estimates it will cost about $1 million a year for each additional soldier sent to Afghanistan. That means a 30,000 troop increase would add about $30 billion a year to the war's soaring cost.
War spending in Afghanistan has more than doubled in the past year, reaching $6.7 billion in June alone. Pentagon officials worry that the rising cost could fuel congressional opposition to Obama's expected buildup. (Reporting by Adam Entous in Washington; Editing by David Storey and Eric Walsh)