U.S. Defence Secretary Robert Gates says Americans should expect a significant U.S. military presence in Afghanistan for another two to four years.

Appearing Sunday on NBC's Meet the Press, Gates said the initial U.S. troop withdrawal from Afghanistan in July 2011 might involve only a small number of troops.

Gates said that just as in Iraq, the U.S. will turn over provinces to homegrown security forces, allowing the United States to bring the number of troops down steadily.

The U.S. defence secretary noted that Afghan President Hamid Karzai talked in his inaugural address about taking over security control in all of Afghanistan in five years.