Before meeting with North Korea’s Kim Jong Un, 35, President Donald Trump felt he enjoyed “a very special relationship” with the dictator. But, historically, what impact does a personal relationship between foreign leaders with opposing ideologies in the voluntary pursuit of peace really have?

Leaders of democracies seem to place significant value on this. Some benefit may exist, but only when a common interest is shared.

Bearing this out most notably was British Prime Minister Neville Chamberlain who clearly believed his personal relationship with Germany’s Adolf Hitler in September 1938 had secured “peace for our time.” He was wrong—a year later World War II erupted.

In signing the Paris Peace Accords in January, 1973, National Security Advisor Henry Kissinger believed his cordial relationship with North Vietnamese negotiator Le Duc Tho achieved peace for Vietnam. He too proved wrong—in April, 1975, South Vietnam fell after the North invaded.

In 2012, President Barack Obama named then Turkish Prime Minister (now President) Recep Tayyip Erdogan as a best buddy. Obama undoubtedly left office still clinging to this belief, ignoring the tsunami of Erdogan-triggered, anti-Americanism that swept over Turkey during that time. This was all part of Erdogan’s agenda to undermine support for democracy, dismantling it at home to direct Turkey’s return to the days of the Ottoman Empire’s caliphate. Thus, Obama’s personal relationship had no positive impact.

Obama’s Secretary of State, John Kerry, firmly believed a close personal relationship with Iranian Foreign Minister Mohammad Javad Zarif would help generate a nuclear deal with Tehran. In 2009, Zarif attended the wedding of Kerry’s daughter to an Iranian-American physician whose best man was Zarif’s son. Kerry credited that relationship, in January, 2016, with generating the release of ten US sailors captured after their disabled boat drifted into Iranian territorial waters. While the good news was the personal relationship contributed to reaching a nuclear agreement, the bad news was it was a one-way friendship, earning Iran a heavily one-sided deal in its favor.

The above represented situations in which ideologically opposed leaders shared no common ground.

Common ground was shared in 1985 when President Ronald Reagan and Soviet Premier Mikhail Gorbachev met in Geneva for the first time. While no earth-shattering agreements were reached, the two developed a good rapport. Gorbachev’s disenchantment not only with his country’s lack of economic viability but his desire to change the system to improve it was a common goal shared with Reagan. As the Cold War wound down, Reagan credited Gorbachev for ending it.

As far as Trump’s special personal relationship with Kim is concerned, it is hard to picture having one with a brutal dictator—one to whom his own security is directly tied to maintaining the status quo in his country. This includes his nuclear arsenal—a sign of military prestige. Surrendering it endangers Kim’s power base, thus impacting his willingness to give it up.

One understands how Trump may feel a special relationship exists. Kim possesses the charisma of his grandfather, coming across personably when necessary with foreigners. In a 1994 meeting with the grandfather, this author witnessed that charisma firsthand. Admittedly, the warmth and humor exuded was disarming, causing one to forget, at least temporarily, it was ice flowing through his veins, evidenced by his brutal reign.

The grandfather’s brutality is exceeded by the grandson, who has invented diabolical ways of executing enemies, including his own family members. Kim relishes tearing victims apart either with packs of wild dogs or artillery guns. Undoubtedly the uncle who nurtured Kim after he first took power felt he had a good personal relationship with him—only to be so executed.

Trump reported he queried Kim about the ill-treatment of American college student Otto Warmbier, arrested for trying to steal a poster. Convicted during President Barack Obama’s presidency, Warmbier was imprisoned for seventeen months before Trump won his release. By then, unfortunately, Warmbier was in a coma, dying shortly thereafter due to complications from brain-damaging oxygen deprivation.

Trump said he accepted Kim’s response he knew nothing about Warmbier’s brutal treatment, later adding he still held Kim responsible for the death. Kim’s alleged ignorance is highly unlikely. North Korea—Alexandria Ocasio-Cortez would be pleased to know—is a country in which not even cows fart without Kim’s permission. For Kim, who thrived on torturing others, it is highly unlikely he had no knowledge.

For the summit meeting, Kim was undoubtedly coached not only by China but also Iran, with which Pyongyang has its own special relationship. Kim assuredly was advised to follow Zarif’s example, similarly milking a special relationship with his counterpart to get whatever he wanted. Kim was probably encouraged before the summit as the US dropped its demand for a full accounting of its nuclear program.

Kim tried to press Trump to lift sanctions. Unlike Kerry who gave in to Zarif, however, Trump walked away, electing no deal over a bad one. (US law constrained lifting such sanctions based on Pyongyang’s slave labor human rights abuses.)

This was bad news for China which banked on the US/North Korea nuclear deal it massaged along to pave the way for a badly-needed US trade deal with Beijing.

The good news from the summit is Trump showed Kim he will not cave on issues critical to US national security. The bad news is Kim will continue delaying actions to denuclearize.

Kim, inevitably, will have to be shown Trump is serious about denuclearization. A good way to start might be announcing he is dusting off “Op Plan 5027.” Developed in the summer of 1994 during the Clinton Administration, it details a U.S. military strike against North Korea.

In 1986, Reagan ordered air strikes against Libya for Muammar Gaddafi’s support of terrorism. They came close to killing him, convincing him to stop supporting terrorism. Similarly, the only way to convince Kim to surrender his nukes is to leave him wondering whether Op Plan 5027 includes taking him out.

Successful North Korean denuclearization turns not on a personal relationship with Kim but on increasing his “pucker factor.”