Asked when it took so long for him to denounce white supremacists, the president had an explanation in mind.
The mayor's statement confirmed that the incident at Parsons Green is being investigated as a terror attack, which makes it the fourth that the United Kingdom has seen this year. I want the facts. I want the facts....
There was talk earlier this year of suspending transatlantic security briefings after details of the investigation into the bombing of an Ariana Grande concert in Manchester, northern England, which killed 22 people, were leaked to the media by USA authorities.
The Metropolitan Police were equally quick to dismiss Trump's accusations that the force was aware of the attacker before the explosion, calling his comments "speculation".
On Friday morning, Trump indicated that he expected harsher penalties for terrorists.
National Security Adviser H.R. McMaster suggested later that Trump was speaking generally. "As London has proven again and again, we will never be intimidated or defeated by terrorism", he said.
"I think he means generally that this kind of activity is what we are trying to prevent", McMaster said.
The president's intervention threatened to place fresh strain on the US-UK intelligence-sharing relationship, which has come under pressure a number of times since he entered the White House.
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.More news: No floor test in TN Assembly till Sep 20 : Madras High Court
The Sun Reports that Mayor of London Sadiq Khan has announced: "a manhunt is underway". He has used the phrase more sparingly since taking office, avoiding it during his remarks on the anniversary of the September 11 attacks.
He added that the travel ban into the United States should be far larger, tougher amid the explosion in London, however, noting that it would "stupidly" not be considered to be "politically correct".
On Friday, Trump again jumped into the fray, promoting his record against extremist militants and saying the government should cut of the internet to such groups.
"Another attack in London by a loser terrorist", Trump added. "The internet is their main recruitment tool which we must cut off & use better!"
"Must be proactive & nasty!"
The president has used attacks before to argue for his ban and to lob trans-Atlantic criticism.
In June, after attacks in the London Bridge area that claimed seven lives, Khan warned locals not to be alarmed by the large presence of armed officers on the capital's streets. We need the courts to give us back our rights.
May protested to Trump after USA officials leaked information about a deadly bombing in Manchester in May.
The bomber's identity and details of the probe leaked to U.S. media before British officials felt ready to disclose them.