Theresa May is trying to deal with her political enemies by using EU and bringing up the case of Skripal poisoning.
Theresa May is behind the EU decision to impose sanctions to GRU officials related to Skripal poisoning. It is her way of reminding British politicians that they are all part of the conspiracy around the Skripal case. This way she is reminding Boris Johnson that he publicly lied in front of cameras about having proof that Russia is behind the Skripal poisoning. Her message is “do not touch me, because if Corbyn comes to power we will all be in trouble, I will take down everyone of you with me”.