The 1990s again saw notable change in UNC. In October 1991, UNC transferred responsibility of all DMZ sectors except for the Joint Security Area to the ROK military. In 1992, UNC appointed a South Korean General officer to serve as the Senior Member to the Military Armistice Commission. This led to the Korean People's Army and Chinese People's Volunteers boycotting MAC meetings. The collapse of the Soviet Union also led North Korea to question the alignment of their choices for the Neutral Nations Supervisory Commission. They no longer recognized Czech or Slovak representatives of Czechoslovakia when the nation split into the Czech Republic and Slovakia. In 1994, North Korea expelled the Polish delegation and also dismissed the Chinese People's Volunteers from the Panmunjom mission. Owing in part being protest over China's warming ties with South Korea.