The Russian Navy announced Friday it would commission the first of its stealthy new Project 677 Lada-class diesel submarines next year.

The deputy head of the Navy General Staff, Vice Adm. Oleg Burtsev, said the sub was already undergoing sea trials from of the St. Petersburg ship yard where construction of the next two Ladas is under way.

The RIA Novosti news service said the Lada class as being built for anti-ship and anti-submarine warfare. The ultra-quiet submarines are equipped with cruise missiles and have an advanced anti-sonar coating on the hull that makes it difficult to detect.

Burtsev said Russia plans to build eight Ladas-class submarines to replace the current Kilo class subs.