President Donald Trump's suggestion that London police could have done more to prevent Friday's homemade bomb explosion drew a quick rejoinder from British Prime Minister Theresa May, who said it's never helpful "to speculate on what is an ongoing investigation".
"It's a bad thing", he said of the London attack. "Must be proactive!" he tweeted.
"Must be proactive!" He then added: "Loser terrorists must be dealt with in a much tougher manner", without giving details of what that meant. In a series of posts, Trump's response to the London terror incident implied that United Kingdom authorities were not acting "proactive" in trying to prevent terror, while also touting the potential of travel bans.
"Asked about a Friday morning tweet in which Trump said the USA ban on travelers from certain countries should be more "specific", Trump said: "We have to be tougher and we have to be smarter". An explosion on a London Underground train on Friday was caused by an "improvised explosive device", British police said.
Mr Trump said he told Mrs May the United States is committed to wiping out terrorism and described her as a "wonderful woman".
So, as Frankie's mower roared into life, Mr Trump turned and strode to the Oval Office to - he said - place a call to Theresa May. and perhaps try to fix some of that damage.
After chairing a meeting of the Government's Cobra emergencies committee, the Prime Minister publicly rebuked the USA president, saying it was not "helpful" to speculate on what was an ongoing investigation. Most of the injuries were flash burns, London's Metropolitan Police said. After two terror attacks in the city in June, Trump seized on the moment.
"We have to be tougher and we have to be smarter", Trump told reporters before going into the Oval Office. We need the courts to give us back our rights.
The Mayor of London's response comes just months after Trump called Khan "pathetic" in the wake of the London Bridge attacks, accusing him of telling Londoners there was "no reason to be alarmed".
After his tweets, and with ties apparently under strain, Trump spoke with May to convey "his sympathies and prayers" for victims of the London attack, the White House said in a statement.
The Supreme Court is scheduled to hear arguments on whether the travel ban is legal on October 10.