Tensions continue to rise between the U.S. and North Korea, as North Korea has detained U.S. citizen Tony Kim as he was planning to fly out of Pyongyang International Airport on Saturday. Kim, also known by his Korean name Kim Sang-duk, had been teaching at Pyongyang University of Science and Technology. On Sunday, North Korea threatened to sink a U.S. aircraft carrier that is conducting military drills, along with Japanese ships, in the waters off the Korean Peninsula.