WASHINGTON — Shortly after Ambassador John R. Bolton was sent to represent the United States at the United Nations, an institution he had long scorned as an anti-American citadel of corruption, he hosted President George W. Bush for a visit.
“Are you having fun?” Mr. Bush asked.
“It’s a target-rich environment,” Mr. Bolton replied.
Mr. Bolton, who takes over Monday as President Trump’s third national security adviser with Syria as his most immediate challenge, and talks with North Korea and the future of the Iranian nuclear deal not far behind, loves nothing more than a good target. Over a long and colorful career he has had many of them: the United Nations, first and foremost. But also the International Criminal Court and the Antiballistic Missile Treaty. North Korea. Iran. China. Russia. The Palestinian Authority. The European Union.
And then there are “the Crusaders of Compromise,” as he terms the elite of the national security world; the diplomats he refers to as “the High Minded,” with the capital H and capital M; “the True Believers” of the arms control priesthood. And, of course, Republicans who succumb to such muddled thinking, like Colin L. Powell, Condoleezza Rice and even Mr. Bush.
But as Mr. Trump’s national security adviser, the targeter is now slated to become the facilitator, charged with mobilizing the policy apparatus rather than simply taking aim at it.
Combative, relentless and proudly impolitic, known for a bushy mustache that is the delight of cartoonists, Mr. Bolton, the enfant terrible of the Bush administration, has a kindred spirit of sorts in Mr. Trump, a fellow practitioner of blowtorch politics. When Mr. Bolton moves into Henry A. Kissinger’s old corner office in the West Wing, it will be a Trumpian marriage of man and moment.
And yet Mr. Kissinger mastered the office by mastering his relationship with a sometimes volatile boss. For Mr. Bolton, the new assignment may require a form of diplomacy that his previous roles did not, one that eluded his predecessor, Lt. Gen. H. R. McMaster, as well as Rex W. Tillerson, the recently ousted secretary of state.
Mr. Bolton may amplify Mr. Trump’s most bellicose instincts, as their critics fear, but the two differ in key areas and even admirers wonder what will happen then.
“How will he manage Trump?” asked Eric S. Edelman, an under secretary of defense under Mr. Bush who was often allied with Mr. Bolton. “Trump may love to see John defending him on Fox News. But when John is going to be responsible for policies, he has very strong convictions on things, some of which won’t line up with the president’s.”
“John’s personality is also fairly explosive like the president’s,” he added. “I don’t know how that will work out. That will be John’s big challenge.”
‘Americanist’ Meets ‘America First’
Mr. Bolton defines himself as an “Americanist” sworn to defend the interests of the United States. Too often, in his view, America has sacrificed its own sovereignty following the chimera of global governance.
“This is almost identical to President Trump’s theme of America First,” said Frederick Fleitz, a former intelligence officer who worked for Mr. Bolton. “Mr. Bolton disagrees with many of the Washington elite, or maybe the international elite, who think globalism or multilateralism should be a priority over the security of the United States. That’s exactly where President Trump is.”
In the world of carrot-and-stick diplomacy, Mr. Bolton is a stick man. “I don’t do carrots,” he has said. Opponents call him a warmonger who never met a problem that did not have a military solution, and he remains a strong supporter of the invasion of Iraq and has made the case for strikes against North Korea and Iran to stop their nuclear programs.
Mr. Bolton insists that he does not relish military action. While he declined to be interviewed for this story, he authorized a longtime assistant, Sarah Tinsley, to forward a comment comparing international relations to a 1980s television commercial declaring Ivory soap 99 and 44/100ths percent pure.
“My belief is diplomatic crises, 99 and 44/100ths percent of them can be resolved with public diplomacy,” Mr. Bolton said. “That’s my view. To those who say I’m going to start a war, that’s what I think.”
Some of Mr. Bolton’s harshest critics are those who once worked with him. They use words like “arrogant,” “backstabber” and “disloyal” and others that cannot be printed in a family newspaper. Some view his ascension to the right hand of an already mercurial president with deep alarm.
“This will be the scariest thing that’s happened to us in 50 years,” said Lawrence Wilkerson, chief of staff to Mr. Powell when he was secretary of state. “Bolton is several things, none of them good. He’s an absolutely brutal manager, treats people like dirt. The stories that have come out are accurate, but they don’t go far enough. And he’s also possessed of some views that are just revolting.”
Revolting to his adversaries or refreshing to his admirers, his views are no mystery to anyone who follows him on Twitter or Fox News. In a town of cautious talking points, Mr. Bolton, like Mr. Trump, finds no virtue in subtlety. “China’s jived us for 25 years.” The Iran nuclear deal “must be ripped up.”
The North Koreans are the “biggest con men in the world,” and their planned talks with South Korea could be a “propaganda stunt” to buy time. “Question: How do you know that the North Korean regime is lying?” Mr. Bolton asked recently on Fox. “Answer: Their lips are moving.”
When on another occasion the Fox host Tucker Carlson said the ouster of Saddam Hussein in Iraq had empowered Iran, Mr. Bolton dismissed him. “No,” he said, “because I think your…