The centrality of Trump to US foreign policy has also become apparent this week. This is more than just a simple truism. On show was the lack of involvement of other parts of the US government that traditionally help shape US decision-making overseas.

Take the president’s extraordinary decision to meet Syria’s new president and former jihadist, Ahmed al-Sharaa, and lift sanctions on Syria. This showed the potential advantage of having foreign policy in one man’s hands: it was a decisive and bold step. And it was clearly the president’s personal decision, after heavy lobbying by both Turkey and Saudi Arabia.

It was seen by some diplomats as the quid pro quo for the diplomatic fawning and investment deals Trump received in Riyadh. Not only did the decision surprise many in the region but it also surprised many in the American government.

Diplomats said the State Department was reluctant to lift sanctions, wanting to keep some leverage over the new Syrian government, fearful it was not doing enough to protect minorities and tackle foreign fighters.

Diplomats say this pattern of impulsive decision-making without wider internal government discussion is common in the White House. The result, they say, is not always positive.