North Korea’s ambassador to the U.N. accused the U.S. on Tuesday of preventing global denuclearization and suggested extended deterrence is nuclear “blackmail” against Pyongyang, days after the DPRK announced it had simulated tactical nuclear strikes on South Korea.

Ambassador Kim Song also criticized the presence of U.S. strategic assets in the region — such as the nuclear-powered aircraft carrier USS Ronald Reagan — as Seoul’s ruling party debates the merits of tactical nuclear weapons on South Korean soil.