President Barack Obama is expected on Friday to unveil his proposal for gradually reducing U.S. troop strength in Iraq. Mr. Obama will make the announcement at Camp Lejeune, a Marine base in North Carolina.  

Thousands of Marines from Camp Lejeune have been deployed to Iraq during the course of the war.

About 500 Marines returned to the base from Iraq last week, and President Obama says he plans to bring many more home in the months ahead.

Phasing out U.S. troop deployments to Iraq was one of Mr. Obama's campaign promises last year.

"In 16 months, we should be able to reduce our combat troops, provide some relief to military families and our troops, and bolster our efforts in Afghanistan so that we can capture and kill [Osama] bin Laden and crush al-Qaida," said President Obama.

In his first full day as president, Mr. Obama met with his defense advisers and discussed ways to draw down the number of U.S. troops in Iraq while ensuring that security needs are met.  

White House Press Secretary Robert Gibbs says the president gave his advisers specific instructions.

"The president asked the national security team to put together a plan that they and he believed would accomplish the goal of removing our combat forces from Iraq in the most responsible way," said Robert Gibbs.

Like many government decisions, this one involved some compromise. Mr. Obama wanted to withdraw troops during a 16 month period. Military chiefs asked for 23 months. They apparently have settled on 19 months, with as many as 50,000 troops staying behind - most as trainers and advisers. That angered some lawmakers in the president's Democratic Party, who want all U.S. forces to leave Iraq.  

Gibbs says Mr. Obama has always talked about the need to leave some troops behind.

"The president also talked on the campaign that some force would remain in Iraq for limited missions, consistent with training and combating terrorism," he said.

Republican Senator John McCain raises a different concern. He was a prisoner of war during the Vietnam conflict and he points out that that war started with U.S. troops acting as advisers.

"The draw down will take place," said John McCain. "We will leave, I've read, as many as 50,000 - quote - 'advisers.' But let's also be realistic. Advisers in any conflict are in harm's way."

McCain is the top Republican on the Senate Armed Services Committee. He was defeated by Mr. Obama in last year's presidential election.