US President Donald Trump plans to expel dozens of Russian diplomats from the US in response to the nerve-agent poisoning of a former Russian spy in the UK, Bloomberg reported quoting a source familiar with the matter.

Trump agreed with the recommendation of advisers and the expulsions are likely to be announced on Monday, the people said, though they cautioned that Trump’s decision may not be final. Trump is prepared to act but first wants to be sure European allies will take similar steps against Russia, aides said.

U.S. officials are working through the weekend to develop a coordinated response with the Europeans, one of the people said, after British Prime Minister Theresa May this week rallied support for a tough rebuke.