Shortly after the explosion on the tube train, the US President tweeted: “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!”
The claim that police may have known the attackers’ identities provoked outrage from the Met and led Theresa May to rebuke her US counterpart, on television and during a later direct phone call.
It was unhelpful to “speculate” on the details of an ongoing investigation, the Prime Minister said.
Mr Trump’s tweet also gave the impression he may have leaked sensitive intelligence, in an echo of the leaks to US media of crime scene photos and other details from the Manchester Arena bombing.
The incident led the UK temporarily to halt intelligence sharing with the US, until Home Secretary Amber Rudd said she had been assured such a breach of confidence would not happen again.
Jeremy Bash, a former chief of staff at the CIA and Department of Defence, said the US and UK had an “intimate, close counter-terrorism partnership”.
He told the MSNBC cable channel: “Whenever there’s a division in the relationship, it’s not only bad for the UK, it’s very bad for the United States. That’s why I think you probably heard an audible gasp come from CIA headquarters, from the National Counterterrorism Centre, up the road in Langley, Virginia, when the President put out his tweet.
“Notwithstanding Theresa May’s politeness, he wasn’t speculating at all. The President was quite definitive. He said that Scotland Yard knew, had actually missed clues, that they had a terrorist in their sights and they dropped the ball, they weren’t, quote, ‘proactive’.
“Now, either he was briefing out intelligence, sensitive intelligence, and spilling that out the public, which is totally inappropriate and damaging, or he was just flat wrong and making our best ally in the world look very, very bad.”
Ben Cardin, a Democratic senator on the body’s foreign relations committee, also said: “I think the Prime Minister of the UK was appropriate in calling the President out.”
And John Cohen, a former counter terrorism official, told The New York Times: “These types of statements – at this stage of the investigation – can undermine law enforcement efforts because it discloses key information that the investigators may be using to locate the attackers, and it could put peoples’ lives at risk.”
Mr Trump later tweeted: “Our hearts & prayers go out to the people of London, who suffered a vicious terrorist attack....”
His national security adviser, HR McMaster, attempted to explain the President’s initial outburst. He said: “What the President was communicating is that obviously all of our law enforcement efforts are focused on this terrorism threat, for years.
“Scotland Yard has been a leader, and our FBI has been a leader. So I think if there was a terrorist attack here, God forbid, that we would say that they were in the sights of the FBI. So I think he didn’t mean anything beyond that.”
Police arrested an 18-year-old man in Dover in connection with the rush-hour bombing. He was detained by Kent Police under the Terrorism Act.
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