Donald Trump addresses a campaign rally in Farmington, N.H., this week. (Reuters/Gretchen Ertl)
Milan Panic, a California businessman and the former Prime Minster of Yugoslavia, is recently the author of "Prime Minister for Peace: My Struggle for Serbian Democracy."

In every recent presidential election, a business leader or two has entered the fray. Most recently, Carly Fiorina and Donald Trump have each argued that their time in the private sector makes them uniquely qualified to run the country.

I, too, once made that claim. After decades as a successful California businessman, I answered the call to serve as prime minister of my former homeland of Yugoslavia.

I quickly learned that politics is another realm with very different rules in play. “If you don’t have experience in how government works,” as former secretary of defense Robert Gates recently noted, “your ability to make the government work is going to be significantly reduced. It’s different than business.”

I learned firsthand how true that is.

In 1992, Serbian leader Slobodan Milosevic asked me to serve as prime minister. Everything about his offer excited me. What CEO has not fantasized about running an entire country? This seemed like an opportunity to leave a legacy on my native land and help it move toward peace and political and economic freedom.

I had grown my pharmaceutical company from an operation in my garage to a multimillion-dollar enterprise, so I felt I knew the obvious path forward for my homeland – follow the rules of business.

At the time, Yugoslavia was under United Nations sanctions, cut off economically from the rest of the world, and breaking apart into separate and warring republics. I thought I could work with the legislature to create an investment and financial environment conducive to economic growth: low inflation, stability and a climate friendly to foreign investors. I planned to hire the best brains from American universities and think tanks to help reorganize the economy. I would bring enemies together and show them it was in their mutual self-interest to stop the interminable fighting. In short, I would give orders and they would happen.

But politics soon proved as murky as business seemed clear. As CEO, I could simply issue directives; my employees would follow my lead. Their jobs, in fact, depended on it. I also had the opportunity to handpick my closest business associates.

Working with politicians was a different story. The legislators I dealt with had their own agendas and constituencies to serve. On a given issue, they would talk the whole thing into oblivion, and nothing would get done. I met dozens of nationalist politicians who were filled with a startling level of vicious xenophobia. These politicians wanted to expand their power base by reveling in imagined slights and blaming everything bad on other religions or ethnicities. When I urged the peaceful recognition of breakaway republics following the borders laid down by Josip Tito decades earlier, one former Yugoslav president told me I had fallen from Mars.

Balkan bureaucracy was also particularly medieval and governed by bizarre laws of inertia: It was hard to tell what, if anything, it was actually doing on a given day.

Even Western diplomats, my supposed allies in modernization, had their own agendas. They would allow clear opportunities for progress to fail because they always expected a hidden agenda. They insisted on working through Milosevic, even when the Serbian dictator was clearly worsening the prospects for peace. Their realpolitik mindset convinced them that Milosevic could become “their” guy, while I was just a “decoration” and a “smokescreen.” When I reached out to Assistant Secretary of State Lawrence Eagleburger about this, he told me plainly that he couldn’t have a glass of beer with me even if I were his grandmother. And when I told Secretary of State James Baker that Milosevic was an anti-American manipulator who would never be their ally, he shrugged. How do we know, he asked, that he won’t be replaced by somebody worse?

Trained as a businessman, I confess I was initially unprepared for the machinations of diplomacy. I had always prided myself on being able to sit down with anyone, talk things out and find common ground. But politics is more often a zero-sum game, where enmity and intrigue often supplant self-interest and simple common sense. The gloomy and paranoid worldview of Milosevic and my counterparts in Bosnia and Croatia was maddening to me. Rather than work toward a future based on pluralism and respect, they were always looking to the past, quick to take slight, and eager for revenge. Once, losing my patience at a diplomatic conference in London, I yelled at Milosevic to sit down — a slight that ignited a personal war between us.

Expecting politics to operate like the business world, I was at times naive, short-tempered and autocratic. When I watch press clips of those days now, I see a man untrained and unprepared for the klieg light intensity of press scrutiny.

One could also argue, perhaps, that I was not autocratic enough. When a coup d’etat to oust Milosevic was proposed to me, I balked, believing that the possibility of violence was too strong. Instead, I ran against the dictator in an open election. After the votes were counted in a process that, according to the Helsinki Commission, was “neither free nor fair,” Milosevic remained in power, and I was forced to leave the country.

In the face of all of this, every small advance forward took a Herculean struggle. It took me years of patience, diplomacy and behind-the-scenes wrangling, both in and after leaving office in 1993, to help bring about a peace conference held in Dayton, Ohio, that would end the war in Bosnia. It took almost a full decade of intense negotiations and incremental gains to help forge a democratic political coalition that could oust Milosevic.

Real political leadership takes humility and hard work. Even if Trump doesn’t yet seem to understand this, he should know that real public service, in business or politics, means bringing people together. His decision to exploit cancerous hatreds against immigrants to fuel his path to power is not just a moral failure. It is the opposite of good business, and I know from personal experience it can lead a nation to terrible tragedy.