Ukraine's President Petro Poroshenko congratulated Theresa May on appointing for UK's Prime Minister Office. He wrote this on Twitter.
"Sincere congrats to Theresa May! Ready to work together for peace & prosperity in Europe and to build on close UA-UK relations", reads the message.
He also thanked ex-PM David Cameron for cooperation and support for Ukraine.
"Grateful to David Cameron for great cooperation & sincere support of UA. All success in future endeavors", Poroshenko wrote.