North Korean State TV airs footage of anti-us demonstrations, as Pyongyang continues to harden its posture.<br/> <br />North Korea has threatened a nuclear strike on the United States and missile attacks on its Pacific bases after new U.N. sanctions were imposed after the country's third nuclear weapons test in February.<br/> <br />Defense Secretary Chuck Hagel says there is nothing idle in the threats.<br/> <br />(SOUNDBITE) (English) U.S. SECRETARY OF DEFENSE CHUCK HAGEL SAYING:<br/> <br />"As they have ratcheted up their dangerous rhetoric and some of the actions they have taken over the last few weeks present a real and clear danger."<br/> <br />Two U.S. F22 stealth fighters took part in joint drills in South Korea in a show of force during annual military exercises, and the U.S. says it plans to send a missile defense system to Guam.<br/> <br />(SOUNDBITE) (English) U.S. SECRETARY OF DEFENSE CHUCK HAGEL SAYING:<br/> <br />"It only take being wrong once and I don't want to be the Secretary of Defense who was wrong o
