It is still less than a month since Donald Trump was sworn in as America’s 45th president, but already he has made it abundantly clear that, when it comes to dealing with the outside world, this presidency will be like no other.

Within hours of entering the Oval Office, Mr Trump was involved in unseemly diplomatic spats with world leaders. A phone conversation with Australian Prime Minister Malcolm Turnbull is said to have ended abruptly when Mr Trump hung up.

Then there is the unpredictable nature of the president’s approach to difficult foreign policy issues such as China. One minute he is giving his support to Taiwan, and the next he is backing Beijing’s One China policy.

Now Mr Trump’s opponents, both at home and abroad, will seize on the resignation of National Security Adviser General Michael Flynn as further proof that the administration is all at sea on foreign policy.