A U.S. Defense Department spokesman says Uzbekistan has restricted American military flights from its soil in recent weeks.
But the spokesman refused to link the change directly to U.S. criticism of the Uzbek government's violent crackdown on anti-government protesters last month.
He said Uzbekistan has stopped allowing U.S. nighttime flights from its air base at Karshi-Khanabad, which American forces use to support operations and supply humanitarian aid to neighboring Afghanistan. He said the U.S. military has been working around the restrictions.
Uzbekistan opened the airfield to U.S. forces in the aftermath of the September 11, 2001, terror attacks in the United States.
Washington in recent weeks has been criticizing the Uzbek government for not allowing an international probe into its handling of last month's uprising in the eastern city of Andijan.
Some information for this report provided by AP and AFP.