UK Prime Minister Theresa May has called for further measures against Russia following the attack on former Russian agent Sergei Skripal and his daughter, Reuters reported.

“Yesterday was a significant moment in our response to this reckless act of aggression, but there is still more to be done as we work with international partners on a long-term response to the challenge posed by Russia,” said the Prime Minister.

According to Theresa May, Sergei Skripal and his daughter remain hospitalized in critical condition.