The move was in retaliation for the expulsion of diplomats by Britain, the United States and their allies. The U.S. Consulate in St. Petersburg will be closed.
https://www.nytimes.com/2018/03/29/world/europe/russia-expels-diplomats.html?mtrref=www.google.com
Foreign Secretary Boris Johnson said that the UK will be at the forefront of international effort to stand up to those who threaten the rules-based system.
Foreign secretary warns of possible disruption to energy supplies or harassment of diplomatic missions in Moscow
https://www.svoboda.org/a/29114699.html
https://www.kommersant.ru/doc/3587663
https://ru.krymr.com/a/29132467.html
https://www.gazeta.ru/politics/2018/03/28_a_11698928.shtml
https://www.kommersant.ru/doc/3587575
http://www.rosbalt.ru/world/2018/03/29/1692610.html
http://expert.ru/2018/03/29/aleksandr-vuchich-obratilsya-za-sovetom-k-vladimiru-putinu/