U.S. President Donald J. Trump has urged tough action against the “animals” behind a “terrorist attack” outside London’s Palace of Westminster Tuesday.

He said the perpetrators were “crazy” on Twitter just hours after a car crashed into a security barrier outside the historic building, in what police are treating as a potential attack.

“Another terrorist attack in London…These animals are crazy and must be dealt with through toughness and strength!” he wrote on the social media platform.

UPDATE – Met Assistant Commissioner Neil Basu: “Given that this appears to be a deliberate act, the method, and this being an iconic site, we are treating it as a terrorist incident and the investigation is being led by Counter-Terrorism Command.” https://t.co/zEL4JCji90 — Breitbart London (@BreitbartLondon) August 14, 2018

London’s left-wing Mayor Sadiq Khan has previously been accused of not being tough enough on terror and has even said attacks are “part and parcel” of life in a big city.

The President told The Sun ahead of his visit to the UK earlier this year: “I look at cities in Europe, and I can be specific if you’d like. You have a mayor who has done a terrible job in London. He has done a terrible job.

“Take a look at the terrorism that is taking place. Look at what is going on in London. I think he has done a very bad job on terrorism.”

London’s Muslim Mayor Tells New York And London to Get Used to Terrorism https://t.co/ICvWDeppc9 pic.twitter.com/XvMpzp7wn2 — Breitbart London (@BreitbartLondon) September 19, 2016

After the Westminster Bridge van and knife attack in June 2017, the President tweeted: “At least 7 dead and 48 wounded in terror attack and Mayor of London says there is ‘no reason to be alarmed!’”

The following day, he added: “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!”

The president has also slammed the Mayor’s record on London’s ongoing crime wave, saying he has “done a bad job on crime, if you look, all of the horrible things going on there, with all of the crime that is being brought in”.

Mr Khan has hit back, claiming the President’s hard stance on radical Islam cases terror attacks, compared him to Islamic State militants, said he was not welcome in London, and backed protests again his visit to the city.