North Korea forces at &lsquo;highest alert&rsquo; against U.S., South Korea &lsquo;imperialist aggressors&rsquo;North Korea&rsquo;s artillery and rocket forces are at the highest combat posture, the country&rsquo;s military warned on Tuesday in the latest in a line of threats aimed at South Korea and the United States.The North Korean army&rsquo;s Supreme Command said it will take &ldquo;practical military action&rdquo; to protect national sovereignty and its leadership in response to what it called U.S. and South Korean plots to attack.The statement, carried by the North&rsquo;s official Korean Central News Agency, cited the participation of nuclear-capable B-52 bombers in South Korea-U.S. drills. (AFP Photo / KCNA via KNS)