Iran–USA–Israel
The war against Iran is Trump's biggest foreign policy failure so far. He underestimated the strength of the Islamic Republic. He damaged the alliance with the Gulf countries, which learned through a bitter lesson that America cannot guarantee their security. Relations with Israel are broken. The world was paying a dramatically higher price for oil because of the intervention. Many of Iran's demands were surprisingly easily met, which confirms that Trump was in a hurry to get out of a war that he should not have entered in the first place.