The United States Defense Secretary Jim Mattis says that America is ready to respond to any North Korean threat. Talking to reporters in Washington after talks with his Japanese counterpart, he warned of strong military consequences if North Korea initiates hostilities. <br/><br/>Mattis said, if North Korea launches a missile towards either Japan, the US Pacific island of Guam, the United States or South Korea, US would take immediate, specific actions to take it down.<br/><br/>North Korea has repeatedly threatened to target Japan, which hosts about 54,000 US military personnel, as well as South Korea and the United States with its missiles.