Leaders of the Russian-led Collective Security Treaty Organization (CSTO) and Eurasian Economic Union (EEU) are meeting in Moscow on December 21.
Russian presidential aide Yury Ushakov said the agenda of a session of the CSTO's Collective Security Council will include choosing a successor for Secretary-General Nikolai Bordyuzha and adopting a statement on the fight against terrorism.
The organization groups Russia, Armenia, Belarus, Kazakhstan, Kyrgyzstan, and Tajikistan.
The Supreme Eurasian Economic Council will also hold a session, during which Ushakov said Russia will suggest taking "joint protective measures" following the establishment of a Ukrainian-EU free-trade zone planned for the end of the month.
The EEU, which currently brings more than 180 million people into a single market, was officially established in 2015 and includes Russia, Armenia, Belarus, Kazakhstan, and Kyrgyzstan.