http://news.yahoo.com/s/ap/us_us_afghanistan

WASHINGTON – President Barack Obama is considering four options for realigning U.S. strategy in Afghanistan, his spokesman said Tuesday, while military officials said the choices involve several ways the president could employ additional U.S. forces next year.

White House press secretary Robert Gibbs said Obama will discuss the four scenarios with his national security team on Wednesday. Speaking to reporters aboard Air Force One en route to Fort Hood, Texas, Gibbs would not offer details about those options. He insisted that Obama has not made a decision about troop deployments.

Gibbs said that anybody who says Obama has made a decision "doesn't have in all honesty the slightest idea what they're talking about. The president's yet to make a decision" about troop levels or other aspects of the revised U.S. strategy in Afghanistan.

Obama and first lady Michelle Obama traveled to Killeen, Texas, Tuesday, where the president spoke at a memorial service for those killed in a shooting rampage at Fort Hood.

Military officials, speaking on condition of anonymity because the decision is pending, said the military services are developing presentations to explain how various force levels could be used in Afghanistan and how various deployment schedules could work, given recent promises to give soldiers more rest time at home.

Military officials have said Obama is nearing a decision to add tens of thousands more forces to Afghanistan, though probably not quite the 40,000 sought by his top general there.

Republican senators planned to send a letter to Obama Wednesday urging him to move quickly to fully answer Gen. Stanley McChrystal's request for additional troops and resources. Officials have told The Associated Press that McChrystal prefers an addition of about 40,000 troops next year.

In their letter, the Republican senators reminded Obama that they have supported his moves on Afghanistan so far but are concerned about the stress on the current U.S. force of 68,000.

"We urge you to move now to fully support Gen. McChrystal's call for resources and troops," the letter reads.

A copy of the letter was provided to the AP.

Gibbs said Tuesday that a decision still is weeks away. He had earlier said no announcement is expected until late this month, when the president returns from an extended diplomatic trip to Asia.

An Army brigade that had been training for deployment to Iraq that month may be at or near the vanguard. The brigade, based at Fort Drum in upstate New York, has been told it will not go to Iraq as planned but has been given no new mission yet.

Military officials said Obama will have choices that include a phased addition of up to 40,000 forces over some six months or more next year, based on security conditions and the decisions of NATO allies.

The Army would contribute the vast bulk of any new commitment, along with a large Marine Corps infusion. Both services are counting on plans for a large withdrawal of U.S. combat troops from Iraq to take place as scheduled next spring.

Even so, it is not clear that large numbers of new forces could go to Afghanistan before March. Administration officials have told the AP that some of the expected deployment would probably begin in January with a mission to stiffen the defense of 10 key cities and towns.

Several officials who spoke on condition of anonymity because the decision has not been made also said Obama's announcement will be much broader than the mathematics of troop numbers, which have dominated the U.S. debate.

It soon will be three months since Afghan commander McChrystal reported to Obama that the U.S. mission was headed for failure without the addition of about 40,000 troops.

The officials, who spoke on condition of anonymity because final plans have not been disclosed, dubbed the likely troop increase as "McChrystal Light" because it would fall short of his request. They also said additional small infusions of troops could be dispatched next spring and summer.

The more gradual buildup, the officials said, would allow time to construct needed housing and add equipment needed for transporting the expanded force.

Besides being sent to cities and towns, the new forces would be stationed to protect important roads and other key infrastructure.

As he makes his decision, Obama told ABC News that he wanted to make sure "that if we are sending additional troops that the prospects of a functioning Afghan government are enhanced, that the prospects of al-Qaida being able to attack the U.S. homeland are reduced."