EU decision to impose sanctions on 4 individuals associated with GRU is preparation of heavy artillery to help Theresa May. The Skripals case will be used whenever it is necessary for Theresa May, which means the case needs to be “hot”. And such kind of news will be periodically escalated. Theresa May is using Skirpal case as an excuse to mobilise EU support. She tricked Brussels by failing to confirm the Brexit deal. She will try to become a leader using anti-Russian actions.
EU ambassadors are governed by the UK and playing its game by agreeing to impose sanctions. They have no choice because May is threatening them to publicly declare a separate position on Russia and that would mean the end of Western unity.