Daniel Fried, assistant secretary of state for Europe and Eurasia, made his comments before a House of Representatives subcommittee on 27 October.
Congressman William Delahunt, a Massachusetts Democrat, told the same hearing that Washington has been too quiet about alleged Uzbek rights abuses.
He blamed it on the Pentagon's use of an Uzbek air base for operations in Afghanistan. Uzbekistan in July asked the United States to leave the base after Washington criticized Tashkent for civilian bloodshed following an uprising last May.
The European Union imposed an arms embargo and visa bans on Uzbek officials after the incident in the eastern city of Andijon, where witnesses said soldiers killed hundreds of civilians.