(CNN) - President Barack Obama made a surprise visit to Afghanistan on Friday to personally deliver holiday greetings to U.S. troops stationed there. The president, who is expected to remain on the ground there for roughly three hours, is slated to address troops at Bagram Airfield. Most of the troops are with the Army's 101st Airborne Division.

He will also visit wounded troops at a hospital on the base, according to reporters traveling with Obama. The president will meet with a total of eight patients - five soldiers and three civilian contractors. He will award four Purple Hearts.

Obama was originally scheduled to travel to Kabul to meet with President Hamid Karzai and greet U.S. embassy staffers, but will stay at Bagram because of poor weather conditions. The trip is Obama's second visit to Afghanistan since he became commander in chief. A major U.S. military review of the war in Afghanistan is due this month, a year after Obama ordered additional U.S. troops to the country as part of a strategy that could bring some forces home as soon as July 2011.

In addition to the troops from the 101st Airborne Division, personnel the president will address in Afghanistan also will include representation from components of all services.