President’s tweet on U.K. attack ‘unhelpful’

President WASHINGTON — Donald Trump on Friday suggested British intelligence officials had been previously aware of the assailant or assailants behind an unfolding terrorist attack on the London subway, an assertion that British officials called unhelpful speculation.

Prime Minister Theresa May alluded to Trump’s Twitter post in an interview with reporters, saying “I never think it’s helpful for anybody to speculate on what is an ongoing investigation.”

Trump had written: “Another attack in London by a loser terrorist. These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!”

Later Friday, Trump said he had been briefed on the London terrorist attack, and he later spoke with May by phone. According to the White House, Trump expressed sympathy for the people injured and promised to continue working with the British to fight terrorism. The White House summary of the call did not address whether Trump and May discussed the president’s tweet about Scotland Yard.

It was not immediately clear who was behind the attack or whether the assailant or assailants had been on the radar of British intelligence, as Trump suggested.

In short remarks to reporters Friday morning, Trump did not elaborate on what he meant in his reference to Scotland Yard.