John Bolton is viewed in Washington as a potentially disastrous gamble

Those who fear President Trump’s instincts and impulses have long taken some comfort in the seasoned advisors around the Oval Office. At least that was the case until last night.

There is General James Mattis at the Pentagon, serving as US Defence Secretary. Rex Tillerson was serving as America’s top diplomat at the State Department. And the President’s national security adviser was the respected 3-star general HR McMaster.

Now that troika of “adults in the room” has just been dismembered. This morning only Mattis remains at his post.

Tillerson was dispatched last week with a ruthlessness that left even this cynical and weary town aghast. He was sacked with a Tweet - and to add to the humiliation, it emerged that he found out about it while sitting on the toilet.

Then late last night HR McMaster was gone as well. At least he sacked by the President face-to-face.

In his place is the controversial right-wing figure of John Bolton, a former US Ambassador to the UN who is loathed by those officials who interacted with him in New York.

Bolton is regarded with suspicion - actually that’s too kind, for he is viewed with contempt - by almost the entire foreign policy establishment here. He was a cheerleader for the disastrous Iraq war. He is seen as an interventionist and a hawk - a strange bedfellow for a President who favours some kind of ‘America First’ isolationism.

In fact, for those who analyse risk for a living, this appointment is seen as a potentially disastrous gamble.

The hostility to Bolton is because he has argued for aggressive actions - and even pre-emptive strikes - in places like Iran and North Korea.

This is a Presidential appointment, so the Senate has no ability to block Bolton taking the job.

So fasten your seat belts. The new combination of Mike Pompeo at the State Department and John Bolton at the NSC means the Iran nuclear deal is probably doomed. And hopes for North Korean diplomacy (despite the imminent summit) has been given a big kicking.

Many of the constraints on Trump have gone. Only Mattis remains as a moderating force around Trump. And goodness knows what he’s thinking this morning.