This is by no means the first time Trump Jnr, who claimed his father's comments about "grabbing" women by the "pussy" are typical among some men and are "a fact of life" a year ago, has launched an attack on Mr Khan.
"We should stand in solidarity with London today and put it bluntly: Donald Trump - you are not welcome in Birmingham". In fact, just before issuing the tweet throwing shade on Trump, NBC Nightly News itself had been studiously reporting on emergency response to the terror attack. K., we will be there - WE ARE WITH YOU.
The comments were in response to a statement by Khan in which he had told Londoners not to be alarmed by the increased police presence on the streets of London. "One of the things the police and all of us need to do is make sure we're as safe as we possibly can be".
Up to now, the president had expressed his views only on Twitter.
"We must stop being politically correct and get down to the business of security for our people", Trump tweeted at 7:19 a.m. ET.
"There's no reason to be alarmed".
Later Khan's spokesman said he was too busy to respond to President Trump's "ill-informed" tweet.
"Sadiq Khan has shown dignity and leadership".
Instead of using this political attention and news cycle to promote unity between the world's religions or propose and promote effective anti-terrorism policies, Trump made a decision to blatantly mischaracterize this terror attack to advance his domestic political agenda and broadly target the religion of Islam. Trump later challenged Khan to an IQ test during an interview on ITV.
Nevertheless, the mayor had been telling people not to be alarmed about increased police presence in the capital and in no way telling people they should not be alarmed by the atrocities themselves. "MSM is working hard to sell it!" he tweeted. "So, the president is right, we should have a substance-based policy debate on gun violence and the solutions to address it, and I'd be happy to meet him anytime, anywhere".
- Former Vice President Al Gore called President Trump's decision to withdraw the USA from the 2016 Paris accord "indefensible".
"That's not me, that's not the London I know, and we aren't going to allow anybody, whether it's Donald Trump or anybody else to divide our community".
The mayor was additionally asked about the prospect of Trump visiting the United Kingdom for a state visit.
Mr. Trump's latest missive at Khan was part of several Monday morning tweets from the president. "And I think on many, many things, Donald Trump is wrong", he said. It is precisely because only the police had guns that they were able to shoot these cowardly attackers dead within 8 minutes of receiving the call, rather than face a deadly gun battle with terrorists that would have resulted in greater loss of life.
This is certainly not the only time that Donald Trump has mixed political aims and the fight against terrorism.
President Donald Trump is again attacking London Mayor Sadiq Khan on Twitter.