MOSCOW - The United States and Ukraine are carrying out observation flights over Russian territory using a US observation plane under monitoring by Russian experts on Aug 22-27, the Russian news agency Sputnik reported on Monday.

The flights will be conducted in accordance with the Treaty on Open Skies signed in March 1992, the news agency reported, citing Sergei Zabello, the acting head of the Russian Defense Ministry's Nuclear Risk Reduction Center.

Russian experts aboard the OS-135B US aircraft will monitor the flights and ensure that the aircraft and the survey equipment used are in compliance with the treaty, he added.

The Treaty on Open Skies, which entered into force on Jan 1, 2002, was one of the confidence-building measures after the end of the Cold War and currently has 34 states parties.