He said the recent U.N. resolution is a "strong message of the international community's opposition to North Korean provocations and these tightened sanctions will impede the growth of weapons of mass destruction programs in North Korea and the United States will be taking additional steps in that regard."
Carney did not elaborate on what those steps might be.
South Korea's top official on relations with the North said Pyongyang's nuclear and missile development is a "cataclysm for the Korean people," and poses a fundamental threat to regional and world peace. "The North Korean behavior is very disappointing," Unification Minister Yu Woo-ik said in a lecture in Seoul, according to his office.
North Korea claims the right to build nuclear weapons as a defense against the United States, its Korean War foe.
The bitter three-year war ended in a truce, not a peace treaty, in 1953, and left the Korean Peninsula divided by the world's most heavily fortified demilitarized zone. The U.S. leads the U.N. Command that governs the truce and stations more than 28,000 troops in ally South Korea, a presence that North Korea cites as a key reason for its drive to build nuclear weapons.
For years, North Korea's neighbors had been negotiating with Pyongyang on providing aid in return for disarmament. North Korea walked away from those talks in 2009 and on Wednesday reiterated that disarmament talks were out of the question.
North Korea is estimated to have stored up enough weaponized plutonium for four to eight bombs, according to scientist Siegfried Hecker, who visited the North's Nyongbyon nuclear complex in 2010.
In 2009, Pyongyang declared that it would begin enriching uranium, which would give North Korea a second way to make atomic weapons.
North Korea carried out underground nuclear tests in 2006 and 2009, both times just weeks after being punished with U.N. sanctions for launching long-range rockets.