Armenia just lost a war [1]. Minsk is swallowed by protests [2]. Kazakhstan is now facing protests [3]. That's half the CSTO members [4]. Meanwhile, Georgia and Ukraine are reminders to disheveled Russians that democracy for former Soviet members can work. (Also Nord Stream [5].)
The cause for action begins and ends with domestic politics vis-a-vis Putin, who has created a system where losing power means loss of property, freedom and potentially life.
[1] https://crsreports.congress.gov/product/pdf/R/R46651
[2] https://en.wikipedia.org/wiki/2020–2021_Belarusian_protests
[3] https://www.nytimes.com/2022/01/05/world/asia/kazakhstan-pro...
[4] https://en.wikipedia.org/wiki/Collective_Security_Treaty_Org...
[5] https://news.yahoo.com/u-senate-vote-cruzs-nord-011608935.ht...