The U.S. and ROK have outlined four principles to be adopted in an effort to counter North Korea’s ongoing asymmetric threat, according to 2015 Strategic Digest published on Tuesday.

The principles include the acquisition, fielding and employment of anti-missile capabilities on the peninsula, further combined training exercises, support for the existing 4D lines of efforts and a commitment to bilateral consultation.

“North Korea continues to challenge the security and stability of the region … In particular, the North’s sustained efforts to develop nuclear weapons as well as ballistic missiles capable of striking the ROK, our allies, and the U.S. Homeland, require