U.S. President Donald Trump said after meeting Vladimir Putin on Monday he saw no reason to believe his own intelligence agencies rather than trust the Kremlin leader on the question of whether Russia interfered to help him win the 2016 election.

On a day when he faced pressure from critics, allied countries and even his own staff to take a tough line, Trump said not a single critical word about Moscow on any of the issues that have brought relations between the two powers to the lowest ebb since the Cold War.

Instead, he denounced the "stupidity" of his own country's policy, especially the decision to investigate election interference.