"The crew of the Severodvinsk nuclear-powered missile cruiser submarine successfully completed the second test launch of the Zircon hypersonic missile. The second test-firing was carried out by the Severodvinsk crew from a submerged position for the first time, from a depth of 40 meters [131 feet] in the White Sea waters, at a conditional target in the Barents Sea," the Russian Defense Ministry said in a statement.
Earlier, Severodvinsk carried out the first-ever on-surface firing.
Earlier this year, Russian Deputy Defence Minister Alexei Krivoruchko announce that state tests of the Zircon missile were going to culminate in 2021 with submarine launches, opening the way for its serial production for the navy in 2022.