The first Russian ‘doomsday’ submarine, armed with underwater nuclear drones, was put into active service in a ceremony Friday amid the country’s invasion of Ukraine.

According to the Washington Examiner, The Belgorod, the first Project 09852 special-purpose nuclear-powered submarine, was commissioned in the northern Russian city of Severodvinsk, the headquarters of the Northern Fleet, according to U.S. Naval Institute News. The ship was launched in April 2019 after its original commission date of late 2021 was postponed due to COVID-19, according to state news agency TASS.

The Belgorod is the first submarine capable of launching the Poseidon, an “Intercontinental Nuclear-Powered Nuclear-Armed Autonomous Torpedo,” the largest torpedo ever created, according to naval expert H. I. Sutton. The nuclear-armed torpedo is twice as large as submarine-launched ballistic missiles and 30 times larger than a standard torpedo.

The weapons system made headlines in May when Dmitry Kiselyov, a presenter for state-owned media company Russia-1, threatened to use the Poseidon to destroy the United Kingdom and Ireland in a nuclear tsunami. He said the weapon’s 100-megaton yield would produce a 500-meter high radioactive tsunami that would turn the British Isles into a radioactive desert, a claim disputed by Western experts.