The authorities in Kiev lay blame for the heaviest fighting in nearly a year on the withdrawal of Russian officers who had acted as mediators.
https://www.nytimes.com/2017/12/20/world/europe/ukraine-war-russia.html
https://www.ft.com/content/ff155500-e5a3-11e7-8b99-0191e45377ec
http://day.kyiv.ua/ru/article/den-planety/moshchnyy-signal-agressoru
http://nv.ua/opinion/yaremenko/chto-izmenit-rezoljutsija-oon-po-krymu-2405793.html
https://www.radiosvoboda.org/a/28928800.html
https://www.gazeta.ru/politics/2017/12/20_a_11501420.shtml
https://www.kommersant.ru/doc/3502363
http://www.finanz.ru/novosti/aktsii/kitay-zabrakoval-ceny-na-rossiyskiy-gaz-1011685032
http://www.kasparov.ru/material.php?id=5A3A542496FD5