Since START treaty was signed he has worked with US-Russia Business Council. Source
7/24/2014 - Burt argued against sanctions on Russia. Source
4/27/2016 – Burt sits on the senior advisory board of Russian Alfa Bank.Source
There was some odd Trump server communication with Alfa Bank. Source
9/9/2016 - Burt is chairman of the advisory council of The National Interest , a publication of the Center for the National Interest, a strongly pro-Russian think tank based in Washington. Source