You will see an increased police presence today, including armed officers and uniformed officers.
"The point is, there is a reason to be alarmed".
Trump commented on the vehicle and knife attack that killed at least seven people in London at the conclusion of a fundraiser for Ford's Theater, scene of one of the most famous acts of bloodshed in American history: the assassination of President Abraham Lincoln.
Later Sunday, Lew Lukens, chargé d'affaires ad interim of the U.S. Embassy in London, contradicted Trump and tweeted that London's response to the attack was "extraordinary" while praising Khan's leadership.
In a new Facebook post on the London terror attacks, former CBS Evening News anchor Dan Rather said, "we must process and think carefully about how our President publicly responded", to the London attacks.
A spokesperson for Khan Sunday called Trump's remark "ill-informed" and said it took the mayor's words out of context. The point is there is a reason to be alarmed. She praised Khan's response to the attack but refused to explicitly comment on the U.S. president's intervention.
Khan is elected as the first Muslim mayor of London.
"After acts of unspeakable cruelty & cowardice, the people of London & the United Kingdom choose resolve over fear".
Asked about the row this morning by the Financial Times, the prime minister said that Khan was doing an "excellent job" and then declined to say anything about Trump when pushed. "Cancel the state visit and tell Trump where to get off", the north London MP wrote.
The attack raised security as a major theme of the general election, set for Thursday 8 June. "This is a man insulting our national values at a time of introspection and mourning".
"It's even more important that we work together with our allies and our friends and our partners - yes, to keep us safe, but also to expand our understanding of what we can achieve together", Clinton said.
Khan himself hasn't responded to Trump's tweets. Trump later challenged Khan to an IQ test during an interview on ITV.
Mr Trump has also been tweeting about his stalled travel ban after the deadly London Bridge attack.
He advocated for a return to the original version of the ban. The Justice Department has been battling in court to have the bans reinstated, and Trump has repeatedly spoken out against the judges opposing him.