Donald Trump already appears to have fallen out with the UK PM and the Mayor of London. The question has to be posed about who is his international allies will be?
If he cannot maintain good relations with the UK then who will he look to? There is also the obvious implication for the EU Referendum as well. If Mr Trump becomes President will he really want to do a trade deal with the UK? Even if he does, what would the terms look like in a potential era of Trump trying to demonstrate the power of the US?
This may look like a spat but it actually says something very important about international politics.
Donald Trump has warned he may not have a "very good relationship" with UK Prime Minister David Cameron if he wins the US presidency.