Transcript for North Korea has yet to charge American Tony Kim with a crime

North Korea upping the ante with the United States with new and troubling move tonight. Taking an American teacher into custody as he was about to return home. And the new threat to sink that U.S. Carrier group. President trump in a new round of phone calls with China and Japan and a new round of meeting with the U.N. Security council. ABC's Bob woodruff in north Korea. Reporter: Tonight, American Tony Kim remains in custody. The 58-year-old professor arrested in North Korea while trying to leave the country. He has yet to be charged with a crime. He is one of three Americans being held. Please save my life. Reporter: The other two serving lengthy prison sentences. Tensions between the United States and the regime is reaching new highs. A message delivered by state-run media warning the aircraft carrier uss Carl Vinson could be sunk with a single strike. The "Vinson," now heading to the Korean peninsula. Welcome to the white house. Reporter: Today, president trump is hosting a rare meeting with the united nations security council, pressuring them to act. People have put blindfolds on for decades, and we have to solve the problem. Reporter: Mr. Trump also spoke by phone with China's president, and the two reafirmed the urgency of the north Korean threat. Trump also accepted president XI's invitation to China later this year. David? Bob woodruff our thanks to you, Bob.

This transcript has been automatically generated and may not be 100% accurate.