Within the next half-hour, President Obama is scheduled to talk to Marines at Camp Lejeune in North Carolina about his plans for withdrawing U.S. troops from Iraq. We'll use this post to live-blog his remarks.

12:05 p.m. ET: Defense Secretary Robert Gates and Joint Chiefs of Staff chairman Mike Mullen just walked in and, along with a crowd of Marines, are listening to the national anthem being sung. And now Obama is here, getting rousing responses to his "Good morning" to Marines, Camp Lejeune and Jacksonville. (Although technically it's the afternoon).

12:10 p.m. ET: Obama pays tribute to "all of our soldiers, sailors, airmen and Marines serving in Iraq and Afghanistan," and to just retired Iraq ambassador Ryan Crocker, "one of the unsung heroes" of the effort.

He says next month will mark the sixth anniversary of the Iraq war. "By any measure this has already been a long war."

12:12 p.m. ET: Obama says members of the military have succeeded "beyond any expectation." He says the situation there has improved, violence has been reduced substantially, al-Qaeda in Iraq has been dealt a serious blow and Iraqi security forces are stronger.

"Iraq is not yet secure and there will be difficult days ahead," he warns. "Too many fundamental political questions ... remain unresolved. Too many Iraqis are still displaced or destitute."

12:17 p.m. ET: "The United States will pursue a new strategy" -- a transition to Iraqi responsibility. Obama says the U.S. cannot sustain indefinitely a commitment that has strained the military and cost $1 trillion, even if Iraq is not perfectly safe or united.

As a candidate I made clear my commitment to a 16-month withdrawal, Obama says. After consultations with military leaders, he's settled on an 18-month timeline.

"By Aug. 31, 2010, our combat mission in Iraq will end," winning his first applause.

He'll keep 35,000 to 50,000 troops there in non-combat missions. Second round of applause when he adds: "I intend to remove all U.S. troops from Iraq by the end of 2011."

12:25 p.m. ET: Obama says Chris Hill, the new ambassador, will "help Iraqi institutions strengthen their capacity to protect the rule of law, confront corruption, and deliver basic services," among other things.

He congratulates Iraqis for stepping back from civil war and demonstrating resilience. "The United States pursues no claim on your territory or your resources. We respect your sovereignty ... we seek a full transition" to Iraqi control, Obama says.

12:30 p.m. ET: The United States will step up diplomacy across the region. The end of the Iraq war will "enable a new era of American leadership and engagement in the Middle East."

He wins applause when he says that at a time when so many institutions and people acted irresponsibly, "so many of you did the opposite. You volunteered to bear the heaviest burden."

You did your duty and now your nation must do ours, he says to more applause. His new budget increases soldiers and Marines to lessen the burden on the military and expands veterans care, he says. Repeated applause in this section, especially when he says "We will raise military pay." He ad-libs, "I figured that'd be an applause line."

12:36 p.m. ET: He acknowledges that some people want to stay longer in Iraq, and others want to leave sooner. He says he's reviewing Afghanistan policy to make sure troops have a clearly defined mission; he'll consult with Congress and foreign allies on future policies, and "I promise you that I will only send you into harm’s way when it is absolutely necessary ... That is the most important lesson of all."

He closes with the story of two young Marines who lost their lives but saved 50 others by stopping a truck loaded with explosives. He warns that there will be more danger and trials in Iraq.

"But thanks to the sacrifices of those who have served, we have forged hard-earned progress, we are leaving Iraq to its people, and we have begun the work of ending this war," he says.

12:45 p.m. ET: White House press secretary Robert Gibbs says Obama called Iraqi Prime Minister Nouri al-Maliki and former president George W. Bush before the speech to let them know what he would say, The Associated Press reports.

12:55 p.m. ET: Cable talkers are fixing on this passage, in which Obama talks directly to his audience, and wondering if this is as far as he'll go in declaring success: "We sent our troops to Iraq to do away with Saddam Hussein’s regime – and you got the job done. We kept our troops in Iraq to help establish a sovereign government – and you got the job done. And we will leave the Iraqi people with a hard-earned opportunity to live a better life – that is your achievement; that is the prospect that you have made possible."

(Photo: Obama greets some Marines after his address. By Jim Young of Reuters.)

Read the full speech here, as prepared for delivery.

(Posted by Jill Lawrence)