After a decade "under the dark cloud of war," President Obama will tell the nation tonight that the U.S. can "see the light of a new day" in  Afghanistan.

"The Iraq War is over. The number of our troops in harm's way has been cut in half, and more will be coming home soon. We have a clear path to fulfill our mission in Afghanistan, while delivering justice to al Qaeda," the president will say, according to excerpts of his remarks. "This time of war began in Afghanistan, and this is where it will end."

The president will cap his surprise visit to Afghanistan with an address to the nation from Bagram Air Base at 7:30 pm (ET). Earlier today the president met with Afghan President Hamid Karzai and signed a Strategic Partnership Agreement that outlines the 10-year relationship between the U.S. and Afghanistan after the American withdrawal.

"Already, nearly half the Afghan people live in places where Afghan Security Forces are moving into the lead. This month, at a NATO Summit in Chicago, our coalition will set a goal for Afghan forces to be in the lead for combat operations across the country next year. International troops will continue to train, advise and assist the Afghans, and fight alongside them when needed. But we will shift into a support role as Afghans step forward," the president will say.

The U.S. and its NATO allies are set to hand off security control to the Afghans by the end of 2014. By the end of September, the U.S. is expected to shrink its force in Afghanistan from roughly 88,000 troops down to 68,000.

"Last year, we removed 10,000 U.S. troops from Afghanistan. Another 23,000 will leave by the end of the summer. After that, reductions will continue at a steady pace, with more of our troops coming home. And as our coalition agreed, by the end of 2014 the Afghans will be fully responsible for the security of their country," Obama will say.

The president, who spent time greeting troops earlier today, will also thank U.S. forces for their service. "This future is only within reach because of our men and women in uniform. Time and again, they have answered the call to serve in distant and dangerous places. In an age when so many institutions have come up short, these Americans stood tall. They met their responsibilities to one another, and the flag they serve under," he will say this evening.