Widely described as a 'fiasco', it's thought the past weekend's G7 summit in Canada could be a turning point in transatlantic relations.
Confidence between President Trump and his allies appears to have fallen to an all-time low.
Vincent Michelot is Professor of American Studies at The Institut d'études politiques de Lyon.
Speaking to Euronews, he said it's the US who could suffer in the long term:
"President Trump's systematic break with accepted norms is not only destabilising, it also leads to a total lack of predictability; everything becomes about him. American power in today's "world order" is diminished. Whereas before, they were the architects of this world order and also, undeniably, the pre-eminent economic power. Today the United States can only impose itself on this world order its economic power alone, knowing that they are in violation of the rules of the WTO, of Gatt and of many other treaties Donald Trump has left or is threatening to leave"
In a series of angry tweets on Sunday, Donald Trump rejected the G7's shared communique.
The President insisted his allies were trying to take advantage of the US over trade and financing Nato.
Vincent Michelot said Trump's tweets have completely destabilised relations among the world's major powers:
"Not only was Trump reluctant to go to the G7, but he also came with demands that include bringing Russia back into the G7, which was almost in itself a provocation. Until now, provocation has been a diplomatic tactic of small dictatorial regimes. And so when we see that provocation becomes a form of American diplomacy, that's where we're left a little astonished."