Relations between the US and its closest allies plunged to new depths on Sunday after the most acrimonious Group of Seven summit in a generation ended with the American president lashing out at fellow leaders and backtracking on a pledge to sign the G7 communiqué.

The west was in disarray after Donald Trump left the summit early, instructed his officials to tear up the bland G7 statement, threatened to impose more tariffs and called the Canadian prime minister “very dishonest and weak”.

As Mr Trump landed in Singapore on Air Force One to prepare for a historic meeting with Kim Jong Un, the North Korean leader, his advisers continued the attack on western allies and, in particular, Justin Trudeau. The Canadian premier and G7 chair had described the US tariffs on steel and aluminium as “insulting”.