The decision has been made President Barack Obama will deploy thousands of more American troops to Afghanistan. He will formally make the announcement Tuesday. Liao Liang takes a look at how Obama's blueprint is shaping up.

These soldiers are among 70-thousand Americans deployed in Afghanistan. Their ranks will soon be boosted by another 35-thousand fellow troops. That's the centerpiece of Obama's revised war strategy in Afghanistan.

The additional soldiers will be deployed to secure population centers, step up the fight against the Taliban and train Afghan security forces to gradually assume control.

The build-up is expected to be phased-in during the next 12 to 18 months.

Obama will outline the plan on Tuesday night from the US Military Academy at West Point, New York.

He is also expected to clarify why the US is fighting the war and lay out a path toward disengagement.

Prof. William Keylor, Boston University, said, "The question is what is the goal? How do you finish this war? When can you announce mission accomplished, and that is a big question I hope he tries to answer."

Washington hopes the strategy will create conditions to allow an eventual US troop drawdown and handover to Afghan forces.

The process will require a three- to five-year period.

US officials said a transition to greater Afghan control could begin quickly in parts of Afghanistan that are more stable.