South Korea says it has its military units ` ` on the highest alert '' It says the units hit targets on the Korean mainland , Hawaii and Guam . `` We are firmly committed to defending the Republic of Korea and Japan , '' he added , using the official name for South Korea . The U.S. says it is ` ` fully capable '' of defending itself and its allies . The North is angry over U.N. sanctions and U.S.-South Korean military exercises .
South Korea says it has its military units ` ` on the highest alert '' It says the units hit targets on the Korean mainland , Hawaii and Guam . The U.S. says it is ` ` fully capable '' of defending itself and its allies . The North is angry over U.N. sanctions and U.S.-South Korean military exercises .