A frigate of the Russian Black Sea Fleet struck military infrastructure in Ukraine with four cruise missiles, the Russian Ministry of Defense reported on Wednesday morning, Reuters reports.

“The crew of a frigate of the Black Sea Fleet was tasked with striking the enemy’s military infrastructure with Kalibr cruise missiles as soon as possible,” the ministry said in the Telegram channel, News.ro notes.

The ministry said “identified targets” were hit. Reuters said it could not independently verify the claim, and there was no immediate comment from Ukraine on Wednesday morning about the infrastructure affected overnight.

A video of the attack posted by the ministry on Telegram showed the ship launching missiles at dawn, but there was also footage during the day.

The Naval Forces of Ukraine reported on Tuesday evening that as of Tuesday evening, the Russian Navy left two submarines with a total of up to eight Kalibr missiles on combat duty in the Black Sea.

“The missile threat level is high,” the Navy of Ukraine reported on the Telegram channel.

The Black Sea became the decisive theater of operations in this 21-month war. Ukraine stepped up air and naval drone strikes against Russian military facilities in the area, which damaged a ship and ship repair facilities in the port of Sevastopol and hit other targets.

Moscow uses its Black Sea Fleet to carry out long-range attacks on Ukraine. But for President Vladimir Putin, the waters that connect to the Mediterranean are also an important springboard to project his power in the Middle East, Europe and the West.

Ukrainian President Volodymyr Zelenskyi said Kyiv’s ability to strike warships and undermine Russian surveillance in the Black Sea undermined Russia’s military efforts and helped Ukraine secure a sea route for grain exports.