North Korea doubled down on its nuclear weapons and missile drive Wednesday, vowing to continue to develop the programs "at a faster pace," one day after the U.N. slapped the isolated nation with the toughest round of sanctions yet over its sixth nuclear test, which experts said may have had an explosive yield of 250 kilotons.

"The adoption of another illegal and evil 'resolution on sanctions' piloted by the U.S. served as an occasion for the DPRK to verify that the road it chose to go down was absolutely right," North Korea's Foreign Ministry said in a statement carried by the official Korean Central News Agency, using the acronym for the North's official name.

The North, the statement added, would "strengthen its resolve to follow this road at a faster pace without the slightest diversion until this fight to the finish is over."