UK prime minister says Nato world's 'most effective military alliance'

British Prime Minister Keir Starmer called Nato "the single most effective military alliance the world has ever seen" on Wednesday, following renewed criticism of the group by US President Donald Trump.

"It has kept us safe for many decades, and we are fully committed to Nato," Starmer told a press conference, after Trump told the UK's Telegraph newspaper that the alliance was a "paper tiger".