The Ukrainian military said that Russia doubled the number of ships on duty in the Black Sea on Friday and suggested that this could be in preparation for new missile attacks, Reuters reported.

Russia’s navy has regularly launched missiles from the Black Sea as part of Moscow’s efforts to target critical Ukrainian and energy infrastructure.

“In the Black Sea, the fleet of warships has doubled since the morning – now there are eight ships,” says the message of the military command of the southern region on Facebook.

“Against the background of enemy activity from the air of a certain type, this may indicate that a missile strike is being prepared, as well as drone strikes,” he said.

One of the ships is a frigate armed with eight Kalibr missiles, the message says.

Ukraine said last Saturday that Russia had launched four Kalibr missiles from the Black Sea, two of which were shot down.

The Russian Black Sea Fleet is based on the Crimean peninsula, which Moscow annexed in 2014.