 According to admiral Foggo, the commander of the US Naval Forces Europe, the Yasen class submarines are "very quiet, which is the most important thing in submarine warfare"..It's claimed that Severodvinsk is far quieter than previous Russian SSNs, capable of 20 knots while running quiet, which is equal to the Seawolf class and inferior only to Virginia (25 knots).Other sources claim that Severodvinsk is capable of even 28 knots in silent mode .