Citing "imperialist aggression," North Korea put its military on high alert Tuesday, escalating its anti-United States and South Korean rhetoric, NBC News reported. A North Korean military spokesman said in a statement, "The U.S. will be wholly accountable for the unexpected horrible disaster to be met by its imperialist aggression forces' nuclear strike means," adding that the country was looking to "keep themselves fully ready to promptly launch operations at any time.” It was the latest in threats from the reclusive communist country, led by Kim Jong Il's son, Kim Jong Un. North Korea declared in March that it is no longer bound by the armistice that ended fighting in the 1950-53 Korean War signed with the United States and China. It is believed the country has the means to create 10 nuclear bombs, but has not yet mastered the technology to deploy such weapons. South Korea, seemingly used to such threats, did not place its military on high alert.