North Korean leader Kim Jong Un, second from left, and Dennis Rodman, right, watch a basketball game between former National Basketball Association players and North Korean players at Pyongyang Indoor Stadium in this undated photo released by North Korea’s Korean Central News Agency. (KCNA/Reuters)

Yes, it’s true — on Friday, Dennis Rodman confirmed on Instagram that he’s heading to Singapore to “give whatever support is needed to my friends, President Trump and Marshall Kim Jong Un.”

This news has caught many — including the president, apparently — by surprise. On Thursday, President Trump said that Rodman had not been invited to the summit but called him a “nice guy.”

Rodman’s “basketball diplomacy” since 2013 involved high-profile visits to North Korea, where he met with Kim Jong Un, the nation’s leader. Rodman also brought along copies of Donald Trump’s books in 2017 and claims to have sold the North Korean leader on the U.S. president.

Rodman told TMZ that he should get some credit for a summit:

“I like Donald Trump. He’s a good friend, and I’ve always asked him to talk to me because the people of North Korea and the government over there asked me to talk to Donald Trump about what they want and how we could solve things.”

Dennis Rodman is the latest in a long line of middlemen

Rodman is far from the first unusual intermediary in U.S. foreign policy. In my book “America’s Middlemen,” I explain how unusual figures — con artists, slaves and escaped prisoners — have shaped the trajectory of American history by doing exactly what Rodman claims to have achieved. They forge the social connections that grease the gears of cooperation and war — but things usually end badly when these types of middlemen are involved.

Rodman has the advantage of being one of the few people in the world who know both Trump and Kim. Unusual diplomatic agents like Rodman have used this special in-between position to influence American history. Here are some other examples.

Jefferson’s war against pirates

The First Barbary War, which began in 1801, was the first overseas conflict fought by the United States. Tripoli had captured U.S. ships and imprisoned its sailors, demanding tribute. The United States chose to fight rather than pay.

The U.S. naval effort did not go well. The USS Philadelphia ran aground, and Tripoli captured its U.S. sailors before a brave U.S. assault party burned the ship.

It was a former slave — James Leander Cathcart — who helped solve the problem for the United States. Cathcart had been captured on a ship in 1785 and was held for 11 years in Tripoli, rising to be Christian secretary to the regime.

Cathcart came up with the idea of forming an alliance with the brother of Tripoli’s leader, as he wrote to Secretary of State James Madison, and “dethroning the present Bashaw & affecting a revolution in favor of his Brother Hamet, who is at Tunis, & thereby insure the United States the gratitude of him and his successors.”

Cathcart sent the designs of a plan to his friend William Eaton, who put it into effect without much authority from the United States. Eaton helped form an army, march across North Africa and attack Tripoli’s second-largest city.

He was neither gifted nor rich, and one colleague pointed out that “He has neither the talent nor the dignity of the character necessary.”

But his time as a slave taught him about the regime and its rulers. Like Rodman, Cathcart traded on his position between societies. He was the only American with an intimate knowledge of both Tripolitan and U.S. politics. His scheme helped end the war.

Middlemen sell America to the world

One advantage that Rodman may have is his salesmanship — which perhaps explains his claim to have helped lay the groundwork for the Trump-Kim summit.

A similar type of salesmanship helped with alliances during the American Revolution, when the Oneidas formed an alliance with the Continental Army against the British, at great cost to themselves. Most historians agree that the architect of the alliance was Samuel Kirkland, a missionary.

Most Iroquois did not trust white settlers because of conflicts over land: A Cayuga leader explained in 1776 that “white people, particularly the Americans, are in nature treacherous and deceitful,” and once they won, they would “turn and fall on the Indians.

The Oneidas reached a different conclusion in part because of Kirkland, who skillfully managed to combine Christianity with Iroquoian religious and social practices, for example, by connecting sharing to charity or likening traditional feasts to communions.

He then used this salesmanship with the Second Continental Congress, hoping to create an alliance. He explained that the Oneida would be valuable allies. He helped craft letters using the fusion of imagery to show how the American desire for freedom echoed political ideals in Iroquois thought.

Kirkland also worked to persuade the Oneida. Two historians concluded that “Like the Oneidas, other Iroquois nations held ideas about freedom in common with the rebels. What they lacked was regular exposure to patriot commentary.”

Kirkland provided the source. He translated the proceedings of the Continental Congress in ways that would appeal to the Oneida, explaining the war from the rebels’ perspective and how the Oneida would fit into America’s future. Kirkland answered concerns about how we could solve things — much like Rodman’s role some 200 years later.

Unprofessional middlemen usually don’t get professional results

Middlemen have also played roles in more recent U.S. foreign policy — Ahmed Chalabi and  Curveball, after all, helped push the faulty reports of weapons of mass destruction to the Bush administration.

There is an unusual aspect to Dennis Rodman. Middlemen — especially those whose diplomatic trips are funded by a cryptocurrency for marijuana — do not usually have direct ties to the White House, simply because presidents generally do not have such unusual friends. Given Donald Trump’s unconventional trajectory to the White House, he relies on very different relationships and information than former presidents.

But history shows that the unprofessionalism of middlemen means that cooperation is often short-lived. The successful new nation later forgot its commitment to the Oneida, removing them from their land. In the Tripoli case, the United States handed over the brother it cooperated with to be imprisoned in Tripoli. Even worse, middlemen helped create an alliance with and arm Philippine rebels in 1899, only to have those guns turned on the United States in the nasty Philippine-American War.

Even if Dennis Rodman earns an assist in Singapore, history isn’t on his side, at least in the long term.

Eric Grynaviski is an associate professor of political science and international affairs at George Washington University. His most recent book is “America’s Middlemen: Power at the Edge of Empire.” It explores how unusual figures, such as traders, missionaries and slaves, have contributed to the shaping of American history by making deals with militias, tribes and rebels.