There’s a clock-like regularity to which members of Donald Trump’s administration undermine exactly the institutions they have been chosen to lead. Lately, Trump is also jettisoning anyone willing to try to restrain the president’s worst and most impulsive instincts. It’s little surprise, therefore, that he would nominate John Bolton, the most anti-diplomacy diplomat to ever see the light of day, to be his new national security adviser.

The firing of Lt. Gen. H.R. McMaster was only the latest in a long string of departures by those I used to consider to be the adults in the room, their far-right views notwithstanding. To be sure, National Economic Council Director Gary Cohn resigned in protest after Trump’s tariffs on steel and aluminum; now, tariffs on China are in the works as well. Secretary of State Rex Tillerson was ousted thanks to a fraught relationship with the president further marred by disagreements on foreign policy issues involving Iran, North Korea, climate and trade. Suspiciously, his firing immediately followed Tillerson’s tough words on Russia about the nerve agent attack in Britain.

But Bolton, Trump’s third national security adviser in just 14 months and a hawk among hawks, is the one who has me the most concerned. There are few people more likely to lead the country into war. Grave concerns about his diplomatic ability are longstanding, as he couldn’t win confirmation as U.S. ambassador to the United Nations during the Bush administration, even from a Republican-controlled Senate. He got the job anyway through a recess appointment, and because national security advisers don’t require Senate confirmation, the five months the Senate took to decide whether he should go the the U.N. in 2005 remain the only extensive examination of his record.

That confirmation battle took place during the early years of the Iraq War, a conflagration that Bolton defends to this day. He was a key advocate of the Bush administration’s main justification for the invasion: that the President of Iraq, Saddam Hussein, possessed weapons of mass destruction that posed a threat to the U.S. This claim was later shown to be false and based on defective intelligence. The Senate Foreign Relations Committee also had copious testimony that, as undersecretary of state, Bolton pressured intelligence analysts into cooking up evidence that Cuba had a biological weapons program. Confirmation hearings revealed that his penchant to subvert the facts in pursuit of his and his allies’ agendas isn’t limited to the aforementioned. “Thousands of pages of documents revealed Bolton, an ally of Vice President Dick Cheney, to be a volatile, aggressive infighter,” wrote The New York Times. “[He] seemed willing to cherry-pick intelligence, steamroll analysts he did not agree with and end-run his State Department bosses in pursuit of an agenda considered bellicose even among Bush administration hawks.”

All signs suggest that Bolton hasn’t changed. In firing Tillerson and McMaster, Trump silenced some of the voices that had tried to mute his more perilous foreign policy impulses, particularly in regards to the Iran nuclear deal. But what he will hear from Bolton will most likely be closer to what Trump himself has advocated. The result? North Korea is probably first on the list of countries with which he is eager to tangle. In an op-ed for the Wall Street Journal, he made the case for a pre-emptive strike: “Pre-emption opponents argue that action is not justified because Pyongyang does not constitute an ‘imminent threat.’ They are wrong.” With Tillerson and McMaster out of the equation, any theoretical talks with Kim Jong Un are much more likely to go badly wrong and result in a bloody-nose strike or worse.

Bolton is also agitating for airstrikes on Iran. He has urged Trump to scrap Barack Obama’s nuclear deal, which blocked Tehran’s path to a nuclear weapon and prevented an arms race in the Middle East. But more generally, it’s likely the mercurial Trump will befuddle and frustrate allies and adversaries even more with contradictory stances on important issues within hours of each other. Instead of Tillerson and McMaster as somewhat stabilizing influences, he will have Bolton as an encourager-enabler. 

Bolton and his unilateralist nationalism are almost certain to accelerate isolation from our allies and the rest of the world. Congress can’t stop his appointment, but must speak out unequivocally against it and reassert its Constitutional responsibility to authorize whether the country goes to war.