WASHINGTON — A planned US troop withdrawal from Afghanistan will start slowly this summer with about 800 soldiers in two Army units due to depart this month, US officers said Wednesday.

The military offered the first details of the troop drawdown after President Barack Obama announced in June plans to pull out 10,000 forces this year and another 23,000 by the end of September in 2012.

"The drawdown will begin this month, as was stated in the president's address," Lieutenant General David Rodriguez, deputy commander of the NATO-led force in Afghanistan, told reporters via video link from Kabul.

"And it will include both combat troops and combat support troops as well as combat service support troops," he said. "It will be a gradual drawdown, and I'm confident that we can draw down those troops through the end of this year and accomplish our mission."

Rodriguez said two Army units, including one in Kabul, would be finishing their tours this month and would not be replaced by other troops.

The units include 300 troops from the Army National Guard's 1st Squadron, 134th Cavalry Regiment in Kabul and about 500 troops in the National Guard's 1st Squadron, 113rd Cavalry Regiment in Parwan, military officers said.

Both units are part of the Iowa National Guard's 2nd Infantry Brigade Combat Team.

Obama ordered a surge of 33,000 additional troops to Afghanistan in 2009 to try to turn the tide of the war but vowed to begin pulling them out this year.

The withdrawal plan described Wednesday indicates US commanders will have virtually the entire surge force on the ground through the summer fighting season, with no major withdrawal of troops until the last months of the year.

A Marine unit fighting insurgents in the southern Helmand province, the 3rd battalion of the 4th Marine Regiment, will be pulling out between November and December, a Marine spokesman told AFP.

Rodriguez had said the Marine battalion would come out as soon as the end of the summer but officials said he made a mistake.