John Bolton has made it into the White House. Does this mean war?

It’s happened.

In the febrile days after Donald Trump’s election, one of the more terrifying prospects was the appointment of John Bolton to a senior position in the incoming administration. Bolton is the hawk’s hawk, the neocon’s neocon (though he rejects that label, preferring “Goldwater conservative” after the presidential candidate deemed too extreme by the American people in 1964). His published work includes “To Stop Iran’s Bomb, Bomb Iran”, “The Legal Case for Striking North Korea First” and “How to Defund the UN”. As George W Bush’s under secretary of state for arms control he was a rabidly enthusiastic supporter of the invasion of Iraq, and seems never to have fallen out of love with the doctrine of intervention, despite the catastrophe he helped engineer.

As Trump re-ran the Apprentice but for the job of America’s top diplomat, dangling the prize of secretary of state in front of Mitt Romney and Rudy Giuliani, Bolton’s name was increasingly mentioned. But there was a sticking point: facial hair. “Donald was not going to like that moustache,” an associate of the president-elect told the Washington Post. “I can’t think of anyone that’s really close to Donald that has a beard that he likes.”

Bolton had fallen foul of the “right out of central casting” test. He didn’t look the part, unlike the don’t-mess-with-me-faced defence secretary James Mattis, or the bullet-headed national security adviser HR McMaster. That and the fact that the Republican Rand Paul vowed to block his appointment, which would have required Senate confirmation (“He should get nowhere close to the State Department.”) As a result, he remained outside the inner circle, having to content himself with opining on Fox News. Until Thursday.

Bolton is now national security adviser-designate, after McMaster was fired (the position doesn’t require congressional approval). And, once again, Trump’s top team looks like a bunch of rats in a sack, with no internal coherence or logic. The president ran as an anti-interventionist, repeatedly complaining about all the money America spent fighting wars, particularly Iraq. His soft line on Russia couldn’t be further from Bolton’s antagonistic approach.

So what does moustache-man’s promotion signal? Is there now going to be a decisive shift in favour of military intervention in Iran, North Korea and elsewhere, as Bolton would no doubt prefer?

The world is right to be nervous. But there is good reason to think that Bolton’s tenure may not mark an ideological sea-change. There are many causes of the Trump administration’s dysfunction. Prime among them is the idiosyncratic criteria the president applies to senior appointments. Candidates are not selected for their ability to all pull in one direction, with a grand strategy in mind. Nor for their intelligence or experience. Mattis didn’t become defence secretary because of his erudition, but at least in part because Trump heard he was nicknamed “Mad Dog”. McMaster wasn’t chosen because of his book about the importance of military men challenging political leaders, but because Trump goes weak at the knees when he sees a three-star general. Bolton wasn’t picked for his penchant for pre-emption, but because he regularly pops up on Trump’s TV, which is almost always tuned to the same channel.

As he attempts to make his presence felt in the West Wing, Bolton is likely to meet resistance from Mattis and the president’s chief of staff John Kelly, who are said to be “sceptical” of him. And he appears to have struck some kind of bargain to moderate his bellicose instincts. One source told CNN’s White House correspondent Kaitlan Collins that “Bolton promised Trump ‘he wouldn’t start any wars’ if he selected him as the new national security adviser”.

But even if he sticks to that somewhat pat promise, we can still expect him to exert influence over the president’s thinking, particularly on Iran, where they two are more or less of the same mind. Both Rex Tillerson, recently sacked as secretary of state, and McMaster, were proponents of maintaining the Obama-era deal designed to put the brakes on Tehran’s nuclear programme. Trump has made no secret of his disdain for it, and now he will be backed up to the hilt by his own national security adviser. So we can expect this enormous diplomatic achievement to be shredded, despite European efforts to the contrary. But “bomb Iran”? So long as there are at least some adults left in the room that’s unlikely. Help us Mad Dog Mattis, you’re our only hope.

• David Shariatmadari is a Guardian editor and writer