https://www.mk.ru/economics/2019/12/20/rossii-prishlos-poyti-na-gazovye-ustupki-ukraine.html
https://www.inopressa.ru/article/20Dec2019/wp/trump.html
https://www.rosbalt.ru/russia/2019/12/20/1819391.html
https://www.bbc.com/russian/features-50857559
https://theins.ru/antifake/193549
One former senior White House official said Trump even stated so explicitly at one point, saying he knew Ukraine was the real culprit because “Putin told me.”
https://www.thedailybeast.com/trump-administration-battles-new-sanctions-on-russia