Following North Korea's announcement that it built a tactical nuclear attack submarine, the U.S. State Department said the North's illegal weapons of mass destruction and ballistic missile programs pose a threat to global peace, security and the nonproliferation regime.

Responding to questions by Seoul-based Yonhap News, the department said in a spokesperson statement Friday that Pyongyang continues carrying out threatening tests and escalating irresponsible rhetoric regarding its weapons program.

It said the U.S. was closely consulting with South Korea, Japan and other allies and partners on coordinating ways to engage the North, deter its provocations and respond to its breach of multiple UN Security Council resolutions.

The state department however refrained from evaluating the capabilities of North Korea's new submarine.

North Korean state media said Friday the regime launched its first tactical nuclear attack submarine capable of conducting an underwater nuclear attack. South Korean authorities have assessed the sub is not likely fully operational.