While Donald Trump relaunched his attack on Sadiq Khan, every mayor in America sent a message of support and solidarity.

Mr Khan has frequently been a foil for criticism from the US President, and Mr Trump began tweeting about him just hours after the attack in London that left seven dead. Even though Mr Khan has roundly condemned the attack and said there was no reason for people to be alarmed by the sight of armed police officers, Mr Trump had said: “At least 7 dead and 48 wounded in terror attack and Mayor of London says there is ‘no reason to be alarmed!’”

On Monday morning, Mr Trump published a new tweet, that said: “Pathetic excuse by London Mayor Sadiq Khan who had to think fast on his “no reason to be alarmed” statement. MSM is working hard to sell it.”

As Mr Trump was engaging in his attack on Mr Khan, the US Conference of Mayors, which represents 1,400 communities with populations of 30,000 or more, sent a message of support to the London mayor and to Londoners.

“The United States Conference of Mayors stands today united with Mayor Sadiq Khan of London and the people of London. We send condolences to family and loved ones of those dead and injured,” said the group.

Sadiq Khan criticised cuts to London's policing budget

“We send praise and absolute respect for the police officers who responded with eight minutes to kill all three of the London Bridge terrorist murderers.

“The Mayors of the USA who haven’t had a terrorist attack know full well that in today’s age of terrorist actions, domestic and international, an attack could happen in their city.”

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Nan Whaley, the mayor of Dayton, Ohio, for four years, said that at a time like this, it was important for community leaders to show support. She told The Independent it was increasingly clear that incidents such as the one that played out in London, could occur anywhere.

“It happens everywhere, so having communities work together and share their support is something that is very important to the Conference of Mayors,” said Ms Whaley, a Democrat, who heads the group’s international liaison committee.

Karen Freeman-Wilson, the mayor of Gary, Indiana, said the organisation felt it was important to send a message of solidarity from people who understood what it was like to be on the ground working with citizens. She said it was too easy for people to act an “armchair quarterback”.

Without naming Mr Trump, she added: “We did not want there to be fear or alarm because of statements made by people who have never held that position.”