The highest decision making body of North Korea, National Defence Commission said, "the country's army and population will legitimately counter with their powerful nuclear deterrence."
North Korea had routinely threatened to deploy nuclear weapons in the past, for instance last Feb 2010 as the US and South Korea prepared for their annual joint military exercise.
US state secretary Hillary Clinton had announced the tightening of sanctions against the Stalinist state.
The move is mainly meant to block financial support for North Korean nuclear-weapon and missile programmes.
The Foreign Ministry in Pyongyang also had warned the US against new sanctions.
A statement said North Korea would expand its nuclear deterrent and resort to "strong physical measures" in response.