North Korea Monday severed an emergency communications hotline with South Korea as its neighbor and the United States began military exercises at a time of ever-escalating tensions on the Korean Peninsula. Seoul said Pyongyang appeared to have disconnected the telephone line on its side of the border village of Panmunjom in the Demilitarized Zone as it had promised to do last week. South Korean calls placed on the hotline Monday morning failed, the South's Unification Ministry was quoted as saying. Two calls are usually placed on the hotline every workday, a ministry spokeswoman said.