US president Donald Trump has vowed that "this bloodshed must end" after terror attacks in London Bridge left seven people dead.
Mr Trump's remarks, made at a Sunday night fundraising event at Ford's Theatre in Washington DC, were his first public comments on the atrocity since he waded into a row with the Mayor of London by posting criticisms to Twitter.
Earlier on Sunday, Mr Trump slammed Sadiq Khan after the mayor sought to reassure people about a stepped-up police presence on city streets.
In a series of tweets, President Trump challenged Mr Khan for saying there was "no reason to be alarmed" by the extra security measures.
Mr Khan's supporters said his comments had been taken out of context.
Mr Trump also repeated calls for his stalled travel ban, took on supporters of stricter gun control, and pledged that the United States would be there to help London.
He also said he would do whatever was necessary to protect the United States from a "vile enemy" that had waged war on innocents for too long.
"This bloodshed must end, this bloodshed will end," he said, with his wife Melania beside him.
Mr Trump made his comments at the conclusion of the event for Ford's Theatre - the scene of one of the most famous acts of bloodshed in American history: the assassination of Abraham Lincoln.
"America sends our thoughts and prayers and our deepest sympathies to the victims of this evil slaughter and we renew our resolve, stronger than ever before, to protect the United States and its allies from a vile enemy that has waged war on innocent life, and it's gone on too long," Mr Trump said.
"As president, I will do what is necessary to prevent this threat from spreading to our shores and work every single day to protect the safety and security of our country, our communities and our people."
In the attack, three men mowed down pedestrians as they sped down London Bridge on Saturday before crashing the vehicle outside a pub.
The attackers, wielding blades and knives, ran to nearby Borough Market and stabbed people in several different restaurants. Seven people were killed and at least 48 were taken to hospital.