The US president has wasted no time in upending the global order in 2026 - Jonathan Ernst/Reuters The dollar has slumped to its lowest level in more than four years in the wake of Donald Trump’s assault on America’s traditional allies. The US currency fell to its weakest level against the euro since September 2021 on Monday, while the pound touched a four-month high. The slump came after Mr Trump threatened to impose 100pc tariffs on Canada over the weekend in a row over Ottawa’s embrace of China. Inv ...