"This decision will not change anything, and the security of the CIS will not be damaged," Sergei Ivanov, who is also a deputy prime minister, said live on TV.
"For at least the last four or five years, Georgia has, in effect, not participated in the activity of the Council of CIS Defense Ministers or any military operations conducted within the framework of the CIS," Ivanov said.
Georgian President Mikheil Saakashvili signed a decree Thursday ending the country's participation in the council.
The Georgian Foreign Ministry said the country aimed to join NATO and could not be a member of two military blocs simultaneously.
The ministry also said the CIS Executive Committee had already been informed of Saakashvili's decision.
The decree, which was made public on the Georgian president's Web site Friday, is dated January 25.