This is stated on the website of the Government of Belarus.
“During the conversation, Sergei Rumas thanked Dmitry Medvedev for his fruitful joint work as the Prime Minister of the Russian Federation, and also noted that he greatly appreciated his personal contribution to the development of Belarusian-Russian interaction and the expansion of integration processes within the Union State and the Eurasian Economic Union,” - indicated in the message.
At the same time, the Belarusian politician expressed confidence that Medvedev could continue to help build a strong Russia and build confidence between the two peoples.
On January 15, the Russian government resigned. Russian President Vladimir Putin shortly afterwards signed a decree appointing Medvedev deputy chairman of the Security Council.
Putin also appointed Mikhail Mishustin the new chairman of the government of the Russian Federation. Prior to that, the State Duma deputies approved his candidacy.