A U.S. nuclear-powered submarine on Tuesday arrived at the southern port of Busan, South Korea, amid tensions on the Korean Peninsula, YTN television reported. The USS Michigan guided-missile submarine has already arrived at Busan, the South Korean military was quoted as saying. The broadcaster did not elaborate on the exact time of its arrival. Although the nuclear submarine is not supposed to participate in any drills or military operations, its call would send a meaningful message to the Democratic People's Republic of Korea (DPRK), said the YTN. At a national meeting held Monday, the DPRK again warned the United States that it would stage preemptive nuclear strikes against American forces. The USS Michigan is one of four Ohio-class ballistic missile submarines loaded with nuclear missiles. The 170-meter-long, 18,000-ton submarine can carry as many as 150 Tomahawk cruise missiles with a range of some 1,600 km. The Michigan's call ...