From Bongino's book, RE: Flynn/Kislyak call origination.

>On December 29, 2016, while Flynn was on vacation in the Dominican Republic just weeks before Trump’s inauguration, he received a phone call from Russian ambassador Sergey Kislyak.88 Earlier that day, President Barack Obama forced the closure of Russian-owned compounds in New York and Maryland as punishment for interfering with the election. This lame-duck move by the Obama administration gave Kislyak a reason to call Trump’s incoming national security advisor.