The involvement in UNOMIG is based on the decision taken by the Federal Council on 8 December 1993. From January 1994 until June 2009, four Swiss military observers were deployed to this mission. In February 2009, the Security Council extended the mandate for the last time until 15 June 2009 under Resolution 1866. When the Security Council debated another extension of the mandate, Russia used its veto, which led to the termination of UNOMIG on 15 June 2009. When UNOMIG was terminated, around 130 military observers from 30 nations were monitoring the conflict parties' implementation of the cease fire. The four Swiss military observers concluded their various tasks and returned to Switzerland in the middle of July 2009.
Please find more information on Swiss involvement in UNOMIG here.