Rudy Giuliani, the former Mayor of New York City, is President-elect Donald Trump’s top choice for Secretary of State, the Associated Press reported on Monday night. Giuliani is an interesting choice for a president who, unlike any of his predecessors, will enter office without a day of government or military service to his name. Having faced criticism from members of both parties about his lack of experience, Trump was widely expected to pick a foreign policy heavy-weight – such as former UN Ambassador John Bolton or Senate Foreign Relations Committee Chairman Bob Corker – as his chief diplomat to compensate for his lack of experience in the field. But Giuliani, who spent most of his career in the Justice Department, is also relatively inexperienced in international diplomacy. So what can we expect from U.S. foreign policy under Secretary of State Giuliani? One incident in particular may shed light on Giuliani’s approach to diplomacy.

In 1997, during Giuliani’s mayoralty, New York City was embroiled in a battle over diplomatic parking tickets. For years, United Nations diplomats in New York City have flouted parking restrictions, knowing that they could legally not pay under their diplomatic immunity. In the first three months of 1997 alone, 35,000 parking tickets issued to diplomats went unpaid. The issue reached in breaking point in 1997 when NYPD officers attempted to tow a double-parked bus filled with Russian diplomats and their families, desisting only when the Russian Mission agreed to pay the tickets in full. UN diplomats responded by threatening to send the matter to the World Court at The Hague.

What is most enlightening about this incident is that Giuliani, as the State Department rushed to broker a solution, had just one suggestion: if they don’t like it, they can leave town. In a statement at New York City Hall in April 1997, Giuliani said, “If they would like to leave New York over parking tickets, we can find another use for that area of town. It happens to be just about the most valuable real estate in the world,” and urged the State Department to not appease the angered diplomats. When the crisis was eventually resolved after two weeks of negotiations between State Department and UN lawyers, Giuliani accused the State Department of caving in to the demands of “the worst kind of deadbeats.”

The incident shows a clear – and somewhat troubling – picture of how Giuliani, as Secretary of State, might respond to international crises. His initial response was to refuse to negotiate. While the State Department rushed to avoid an international incident, Giuliani refused to cooperate and mocked the proceedings from the sideline.

Giuliani based his decision on the presumption that he was negotiating from a position of strength. In his view, the UN had two choices, both of which were equally acceptable to him: either pay the parking tickets, or leave New York City and allow Giuliani to “find another use for that area of town.” This absolutist approach left no room for compromise, and it was only through the efforts of the State Department that the matter was settled.

Giuliani has taken a similar “all-or-nothing” approach in his statements on the campaign trail this year regarding the Iran nuclear deal. Calling it “one of the worst deals America ever made” at this year’s Republican National Convention, Giuliani pledged that the Trump administration would reject any agreement that did not result in a “non-nuclear Iran.”

These tactics are in line with Trump’s own statements on statecraft. In his book, The Art of the Deal, Trump writes that negotiators must “be willing to walk away” if the price isn’t right. And throughout the course of his campaign, Trump has repeatedly criticized the Obama administration for its apparent “desperation” in negotiating a settlement with Iran. “I mean [John Kerry] has to immediately say this is what we want and if he doesn’t get it, he’s got to walk,” Trump told Fox News host Bill O’Reilly in March 2015.

The absolutist approach that Giuliani and Trump favor carries the great risk that the other party will walk away. And when that happens, the consequences can be disastrous. Had the Obama administration pressed for a “non-nuclear Iran” – as Trump and Giuliani called for – it is possible, if not likely, that Iran would have walked away from the table entirely, as they rely heavily on nuclear energy to meet their growing demand for electricity. This might have led to Iran continuing its nuclear weapons program. And, without the watchful eye of IAEA inspectors, Iran could have developed a nuclear bomb within just 2 months.

Additionally, Giuliani has clearly displayed his view of negotiation as an adversarial process. In a 2007 essay, he wrote, “Those with whom we negotiate – whether ally or adversary – must know that America has other options. The theocrats ruling Iran need to understand that we can wield the stick as well as the carrot, by undermining popular support for their regime, damaging the Iranian economy, weakening Iran’s military, and, should all else fail, destroying its nuclear infrastructure.”

Trump and Giuliani share this view of negotiation as a competition between two antagonistic parties, rather than a forum to find common ground on issues of mutual interest. And while Trump views himself as a business expert, leading negotiation experts have criticized his tactics. Bob Bordone, the founding director of the Harvard Negotiation and Mediation Clinic, wrote that “Trump perfectly embodies the techniques and stances we do not advocate. His behavior suggests that negotiations are always played out on win/lose terms; that the party who prevails does so by smiting or crushing the other; that any effort to make an agreement a good deal for the other party is ‘weak’ negotiating.”

The underlying problem with this, Bordone writes, is that “bullying is a bad strategy.” A successful negotiation results from “engaging others where they are at, finding ways to use the considerable clout of the U.S. to advance our national interest and to present choices that are easy for our allies and our enemies to say yes to.”

It’s easy to dismiss Giuliani’s remarks on the Iran nuclear agreement as campaign bluster and his position vis-à-vis the United Nations’ parking issues as political expedience; indeed, his hardline stance was met with widespread approval among New York City drivers. But these incidents offer insight into how a potential State Department under Giuliani would operate. They suggest that, as our Secretary of State, Giuliani would opt to look tough rather than compromise to reach a mutually-agreeable solution. For Giuliani, the goal of diplomacy would be to win, not to solve the problem at hand. And that is a dangerous trait to have in our nation’s chief diplomat.