The June 12 Singapore summit seems to have ended with an outcome satisfying to both leaders. President Trump had the chance to look like a statesman and peacemaker (even as critics bemoan the concluding agreement’s resemblance to past statements.) Kim Jong Un was able to present himself as a global player on par with the leader of the world’s most powerful nation – and apparently without giving away much in return.

If history is any indication, though, Pyongyang is highly unlikely to leave it at that.

What might Kim want in exchange for good behavior – more than sanctions relief, international legitimacy, or a White House state dinner? The answer, judging by experience, is simple: money. Pyongyang may financially extort the United States or its allies for “aid” in the form of money transfers, so that Trump can continue to claim credit for “solving” North Korea. And if Trump stops paying, North Korea has many tools at its disposal to hurt Trump’s chances of reelection.

Forget “The Art of the Deal” or North Korean propaganda tomes about its dear leaders. To understand how Pyongyang may behave following the historic – and historically disappointing – summit, one should read about former South Korean President Lee Myung Bak’s negotiations with his truculent neighbor.

In his 2015 memoir entitled “The Times of the President,” Lee recounted his 2009 experiences dealing with Kim’s father, Kim Jong Il, over how to arrange a summit between the two sides. As a precondition for the meeting, Kim asked for a bribe – and not a small one. He demanded 400,000 tons of rice, 300,000 tons of chemical fertilizers, 100,000 tons of corn and $10 million worth of aid for road construction. To top it off, Pyongyang also demanded $10 billion in seed money to start an economic development bank – a figure that was almost half of the country’s estimated 2009 gross domestic product, and a sum that Kim almost certainly would have used as his private piggy bank.

And while the numbers may have been unreasonably high, the request wasn’t. Lee’s two immediate predecessors held summits in Pyongyang with the North Korean dictator, in 2000 and 2007. To arrange the first summit, Seoul had facilitated the transfer of $500 million to Pyongyang, $100 million of which was government money. When news of the “cash for summit” scandal broke in 2003, it seriously tarnished the legacy of the then ex-President Kim Dae-jung – a warning for Trump about the reputational costs of bribing the North Koreans.

Lee’s anecdote illuminates what type of economic development Pyongyang might desire. Not economic reform while maintaining tight political control, like China, and not opening up North Korea’s beaches to “the best hotels in the world,” as Trump said in his rambling press conference following the summit. What such an optimistic view tends to neglect is the balance of economic power on the peninsula. If North Korea opens itself up to foreign investment, it is essentially making itself vulnerable to control by the South, whose economy is approximately 50 times larger than that of its neighbor to the north. Small wonder that the Kims have always preferred economic development through kleptocracy: more Zimbabwe than Vietnam.

Pyongyang has little compunction about asking for money. As anyone who has ever eaten or drank with North Korean government officials knows, they almost never pick up the tab. Singapore spent roughly $15 million on the summit, including the costs of the North Korean delegation, and Kim flew in on an Air China plane – in part because it symbolized his need for Chinese help, and in part because he almost certainly didn’t have to pay for it.

Of course, Kim is different from his father. He might want North Korea to move in the direction of China, Vietnam or tiny Laos – less repressive, wealthier communist dictatorships. And he has emphasized economic development more than his predecessor. But a large cash injection is safer for Kim than liberalizing his economy and allowing foreign ideas and influence to threaten his rule.

What happened when Seoul didn’t pay in 2009 should serve as a warning to Trump. Several months after Lee rejected the offer, tensions surged. In March 2010, Pyongyang sank the South Korean military vessel “Cheonan,” killing 46 South Koreans. In November 2010, Pyongyang shelled a South Korean island, killing four South Koreans, injuring 19 and nearly inciting a war.

Kim might see murdering Americans as too risky. But he could certainly test more missiles or nuclear weapons, belying Trump’s claim that there will be “no more rocket launches, nuclear testing, or research” and making Trump seem weak on national security. Even more subtly, he could privately threaten to do those things near Election Day, as a reminder to keep the money flowing. Russia interfered in the 2016 election. 2020 could be North Korea’s year.