President Donald Trump's son has come under fire for criticising London's mayor, shortly after a terror attack on the UK capital killed three people.
Donald Trump Jr tweeted an article written last year, in which Sadiq Khan said terror vigilance had become "part and parcel" of life in a global city.
Mr Trump quoted the headline and tweeted: "You have to be kidding me?!"
He angered many Britons who accused him of exploiting the tragedy and implying the quotes were made after the attack.
Dozens were hurt in Wednesday's attack, when an assailant drove a car through pedestrians on Westminster Bridge and then fatally knifed a police officer who tried to stop him entering the Houses of Parliament. He was then shot dead.
Two hours later, Mr Trump tweeted an article from the Independent newspaper in September 2016.
In the article, Mr Khan was speaking shortly before a meeting with New York Mayor Bill De Blasio, on the day after three bombs exploded in New York City and nearby towns, wounding 29 people.
The attacks had given him a sleepless night, he said, as he pondered the dangers faced by big Western cities like New York and London.
"Part and parcel of living in a great global city is you have to be prepared for these sorts of things, you have to be vigilant, you have to support the police doing an incredibly hard job, you have to support the security services," he said.
On Wednesday, after the attack in Westminster, the mayor said that Londoners "will never be cowed by terrorism" and that the city stood together in the face of those seeking it harm.
Mr Trump's tweet incensed many British people on Twitter, including MP Wes Streeting, who called him a "disgrace" for exploiting the tragedy.
Others accused him of implying that Mr Khan's comments were made after the attack.
Mr Khan, London's first Muslim mayor, has previously clashed with Mr Trump's father, in January denouncing the US president's travel ban as "shameful and cruel".
Last year, he accused the then-candidate Trump of being "ignorant" about Islam.
Mr Trump responded by challenging the mayor to an IQ test.