Russian President Vladimir Putin has criticized the US and its NATO allies for conducting unscheduled drills in the Black Sea, calling them a serious challenge to Moscow.
He said in an interview with a state television which was aired on Saturday that strategic bombers were also deployed in the drills.
The Black Sea borders on the southern regions of Ukraine including Crimea, which was annexed by Russia seven years ago.
Russia is reportedly deploying about 90,000 troops near the Ukrainian border.
The Russian president also accused the US of supporting Ukraine's use of Turkish made drones in October to attack pro-Russian armed groups in violation of a ceasefire agreement.
Separately Putin had branded the actions of the forces of the US and its allies "provocative" in the Black Sea in a telephone conversation with German Chancellor Angela Merkel on Thursday.