Nato countries' pledge to spend 5% of their economic output on defence is Donald Trump's 'biggest foreign policy success,' the alliance's chief has said. In an interview with the BBC, Mark Rutte said it was thanks to Donald Trump that Nato was 'stronger than it ever was', adding that Trump 'is good news for collective defence, for Nato and for Ukraine'. The US leader has harshly criticised European allies for spending very little on defence - even threatening to withdraw US protection if they fail to do so. The Nato chief has warned that Russia could attack allies within the next five years; Russia's President Vladimir Putin dismissed such talk as 'hysteria'. Rutte praised Trump's efforts to find an end to the war, referencing ongoing negotiations for a Trump-proposed peace plan that includes security guarantees for Ukraine. Despite criticisms from Moscow, NATO officials remain firm in their commitment to strengthen defense measures against potential Russian aggression.