On January 6, Russian paratroopers from the Collective Rapid Reaction Force (KSOR) of the Collective Security Treaty Organization (CSTO) began arriving in Kazakhstan. This marked the start of the first military operation by the combined forces of the six former Soviet states that make up the military alliance, which has existed now for nearly 20 years. The legality of today's operation in Kazakhstan is questionable, insofar as the use of collective force in the absence of external aggression against a CSTO member state is not codified in the organization's charter (though neither is it strictly prohibited). In the past, CSTO members have been reluctant to treat domestic turmoil as a collective security threat. In fact, CSTO states have refused multiple times to deploy combined rapid reaction forces due to the lack of external aggression in a member country experiencing a crisis.