Russia has ordered two American military attaches at the U.S. Embassy in Moscow to leave the country following the expulsion of a pair of Russian diplomats from Washington, U.S officials said Thursday.

"We can confirm that the two individuals have been asked to leave," said Gonzalo Gallegos, a State Department spokesman. "We object to this action but we will comply with the Russian government's request."

In Moscow, the Russian Foreign Ministry declined to comment.

U.S. officials played down any linkage between the expulsions of the Americans, which were ordered on April 28, and the U.S. decisions to expel the Russian military attaches. One Russian military officer was ordered to leave Washington on November 6, 2007. The second was ordered to leave on April 22, officials said.

One official, speaking on condition of anonymity due to the sensitivity of the matter, said the United States viewed them as "separate incidents."

The officials declined to discuss the reason for the expulsions, but noted that none of the military attaches involved had been declared "persona non grata" or was accused of specific wrongful conduct, such as espionage.

News of the expulsions comes at a time of uncertainty in U.S.-Russian relations with the arrival in power on Wednesday of new Russian President Dmitry Medvedev and his former boss Vladimir Putin becoming Prime Minister.