The U.S. Department of Defense has called North Korean missiles an ongoing and extraordinary threat. 

In the latest Missile Defense Review released on Thursday, the Pentagon's said while a possible new avenue to peace now exists with North Korea, it continues to pose an extraordinary threat and the United States must remain vigilant. 

The report assessed that North Korea has invested significant resources in its nuclear and ballistic missile programs over the past decade and is moving toward being capable of attacking the U.S. mainland. 

The report was released as North Korea's top negotiator Kim Yong-chol was headed for Washington. Kim is expected to hold talks with Secretary of State Mike Pompeo and possibly meet President Donald Trump.