sentences:  The two countries nullified their earlier friendship and cooperation treaty in 1995, and in 1999, North Korea shut down their embassy in Ulan Bator on the occasion of an official visit Kim Dae-jung, the first such visit by a South Korean president.Mongolia had previously expelled two North Korean diplomats for attempting to passcounterfeit United States one-hundred dollar bills.Subsequently, Mongolia began to intensify its policy of engagement with North Korea, with the aim of improving relations.In 2002, Paek Nam Sun became the first North Korean foreign minister to visit Mongolia in 14 years.