North Korea Threatens To Sink U.S. Carrier

North Korea could reduce a U.S. strike force to a sea wreck if it's provoked, the country's propaganda outlets said Monday, adding to tensions on the Korean Peninsula. With the threat of a nuclear test in North Korea looming and another U.S. citizen reportedly detained there, China's President Xi Jinping is urging President Trump to avoid escalating the situation.

The two leaders spoke by phone Monday, according to Chinese state media CCTV, which reports that Xi told Trump he "hopes all parties remain restrained instead of intensifying the situation."

The phone call comes amid threats from North Korea that it will sink a U.S. Navy strike group that's led by the USS Carl Vinson aircraft carrier; it also follows reports from a North Korean university that one of its lecturers, who holds U.S. and South Korean citizenship, has been detained.

"In a statement, [Pyongyang University of Science and Technology] said that its adjunct professor, 58-year-old Tony Kim, who also goes by Kim Sang-duk, was detained at the airport in Pyongyang as he was about to leave the country on Saturday local time," NPR's Anthony Kuhn reports. "The university said Kim's detention had nothing to do with his academic work. So far, North Korea has remained silent about Kim's detention."

There is wide speculation that North Korea could be planning to carry out a nuclear test on Tuesday, timed to coincide with a celebration of its military's founding anniversary.

On Monday, North Korea issued new threats against the U.S., which it accuses of plotting an invasion. From South Korea's Korea Herald comes this description of the regime's reaction to American warships sailing closer to the peninsula:

"The world would clearly see how the US' rash, arrogant aircraft carriers turn into a lump of scrap metal and gets buried at sea, and how the country vanishes from the Earth," state-run website Uriminzokkiri said.

"Our super-hard-line responses include sudden, pre-emptive strikes involving land, naval, underwater and airmobile assets."

The USS Carl Vinson's strike group is currently in the Philippine Sea, where it's taking part in joint exercises with Japan's Maritime Self-Defense Force, including two Japanese destroyers. The Nimitz-class aircraft carrier was rerouted toward North Korea earlier this month, after initial confusion over its strike group's deployment - including a statement by President Trump that he was sending "an armada" to the Korean Peninsula.

It's not yet clear why Kim might have been detained, other than as a possible bargaining tool for North Korea in international negotiations over its nuclear program. The country also faces a dire need to restart its trade in coal and other items with China.

"China is very much the economic lifeline to North Korea," President Trump said in a tweet Friday, "so, while nothing is easy, if they want to solve the North Korean problem, they will."

Kim is at least the third U.S. citizen in North Korea's custody. Most recently, University of Virginia student Otto Frederick Warmbier was arrested in early 2016 and sentenced to 15 years' hard labor over allegations that he tried to steal a propaganda poster at a hotel.

Warmbier's sentence is nearly identical to that of missionary Kenneth Bae, who was released in 2014 along with his fellow American Matthew Todd Miller.