MOSCOW, Dec. 23 (Xinhua) -- Russia on Monday put into service its second Borei-class nuclear submarine, nearly one year after the first one came into use in January.

Speaking at the launching ceremony of the submarine named Alexander Nevsky, President Vladimir Putin said the vessel is a completely new strategic missile carrier.

"Equipment of that class should become a cornerstone of the sea-based part of our nuclear triad," said Putin via video link.

The submarine, whose construction started in 2004, was put afloat in the White Sea port of Severomorsk, home of the Russian Northern Fleet.

A third sibling submarine is expected to be put into service in 2014.

According to Putin, the Russian Navy will be equipped with eight Borei-class and eight multi-target Yasen-class nuclear submarines by 2020.

He added Russia will build more non-nuclear multi-target submarines and develop coastal naval infrastructure.