The Pentagon named North Korea a "persistent threat" in its updated Strategy for Countering Weapons of Mass Destruction on Thursday. North Korean leader Kim Jong Un this week officially named North Korea's growing nuclear arsenal a "basic law of the state." Photo by KCNA/ UPI.. | License Photo Sept. 29 (UPI) — The U.S. Defense Department identified North Korea as a "persistent threat" in a new security update, warning that the isolated regime has developed the capability to use nuclear weapons at "any stage of conflict." The assessment came in the Pentagon's new Strategy for Countering Weapons of Mass Destruction,…