This post has been updated with a statement from Chief of Naval Operations Adm. Mike Gilday.

Three Russian guided-missile cruisers have been arrayed across the Black Sea and the Mediterranean Sea to counter three NATO carrier strike groups, causing concern in the Pentagon, a U.S. defense official told USNI News on Tuesday.

As of Monday, the three Slava-class cruisers were operating in and around the Aegean Sea – RTS Moskva (121) in the Black Sea, RFS Varyag (011) south of Italy and RTS Marshal Ustinov (055) off the coast of Syria, near Russia's naval base in Tartus.

Moskva is based in the Black Sea, while Marshal Ustinov traveled from the Northern Fleet and Varyag from the Pacific Fleet. Ustinov and Varyag entered the Mediterranean from opposite ends earlier this month.

The three 11,500-ton Slavas were designed around launchers that can hold 16 SS-N-12 Sandbox anti-ship cruise missiles – each about the size of a telephone pole. Developed in the 1970s, the Slavas and the Sandboxes were designed to take on U.S. and NATO aircraft carriers by overwhelming them with a barrage of high-speed cruise missiles to sink ships.

The position of the cruisers around the Aegean is a complication for the U.S., Italian and French carrier strike groups that have been operating in the Mediterranean the last several weeks.

Russian surface action groups as of Feb. 21, 2022. USNI News Graphic