HELSINKI — I was the U.S. ambassador to Russia for two years and worked on Russia policy for the Obama administration for three years before that. I never had my own one-on-one meeting with Russian President Vladimir Putin. But I did participate in a half-dozen sessions with Putin alongside President Barack Obama, Vice President Joe Biden, national security adviser Tom Donilon and Secretary of State John F. Kerry. I have followed and written about Putin’s career since first meeting him in the mayor’s office in St. Petersburg in the spring of 1991. President Trump may think Monday’s summit will be easier than meeting with U.S. allies last week. But if he decides to do any serious preparation before he sits down with Putin, here’s what he should know.

First, Putin prefers small groups. When I was in the government, we had to fight constantly with Putin’s protocol team about the number of people allowed to attend his meetings. We always wanted more; Putin’s team preferred less. In his first meeting with Obama in 2009, we could not persuade Putin’s protocol people to allow our ambassador to Russia at the time, John Beyrle, to attend. When Hillary Clinton first met with Putin in Moscow as secretary of state in 2009, I was Obama’s senior adviser for Russia at the National Security Council. I was walking into the room with her when one of Putin’s assistants grabbed my arm and escorted me to a holding room with other U.S. officials. When Donilon met with Putin in 2012, Putin’s staff made several senior members of our delegation sit in cars outside the compound walls of his country estate. As ambassador, I was the only other American allowed at that meeting.

Second, Putin is extremely confident — some might say arrogant — in his views about international affairs. He was not always this way. Putin was an accidental president, chosen by Russian President Boris Yeltsin as his successor in 1999; the Russian voters simply ratified Yeltsin’s choice. Back then, Putin was unsure of himself in foreign policy. He listened to others, both in his government and to other heads of state. But now, he has been on the job for two decades, save for a brief interregnum when he switched posts with his prime minister, Dmitry Medvedev. Today, he listens to no one; not his national security advisers, not Foreign Minister Sergey Lavrov, and most certainly not to Trump. Putin knows it all.

In fairness to Putin, he is well-versed in international issues by now, especially after overseeing Russian military interventions in Ukraine and Syria, cyber interventions and propaganda operations in the United States and ties to autocrats in North Korea and Iran now for nearly two decades. His theories are flawed; his prescriptions are dangerous. But he knows the details of these issues way better than Trump, or indeed almost any other head of state in the world. That’s why the extended one-on-one meeting with Trump planned for the summit gives Putin a huge advantage.

Third, Putin — according to Putin — has never done anything wrong. In his view, tensions in U.S.-Russian relations are all Obama’s fault, just like they were all the Bush administration’s fault before Obama took office. In his first meeting with Obama in Moscow in July 2009, Putin explained as much about the Bush administration (interestingly, he did not assign fault to Bush personally, but rather blamed those around him), going on for an entire hour without interruption to chronicle all of the United States’ mistakes up to then. So, Putin will be waiting for concessions, rhetorical and substantive, from Trump to get our bilateral relationship on track. Putin, though, will never offer a real concession. He rarely even engages in negotiation. The idea floated by Trump recently that Putin might do him a favor and get out of Ukraine or Syria is laughable. Putin does no one any favors. Geopolitics for him is a zero-sum game.

Fourth, Putin is a persuasive storyteller. In my view, his interpretations of historical events are incomplete, skewed and wrong. But if you don’t know the facts, his arguments can sound persuasive. In his meeting with Obama in June 2012 in Los Cabos, Mexico, Putin articulated a forceful argument for why strongmen had to guide evolutionary modernization in the Middle East. He portrayed both Syria’s Bashar al-Assad and Egypt’s Hosni Mubarak as such leaders and berated us for giving up on Mubarak too soon. He made clear that he would not do the same to Assad, not because he had a strong personal relationship with the Syrian dictator, but because there was no alternative. As I listened, I thought of dozens of flaws in his analysis. But if I didn’t know the history of the region or the academic literature on transitions from authoritarian rule, Putin would have sounded convincing. I worry about the lecture Putin might give to Trump about Arab culture or Crimean history. I’m not confident that Trump knows the details of these issues well enough to push back.

To tell his stories, Putin uses blunt, simple, colorful language. The change in rhetorical style between the refined Medvedev and cruder Putin was striking when they switched roles. Trump will like Putin’s style.

Fifth, Putin can be both abrasive and charming. I’ve seen both negotiating strategies in person. With Trump, Putin will be in charming mode: He will seek to bond over their common disdain for the media, the “deep state” and international institutions. Putin will have Trump nodding along in agreement within minutes. He is good at demonstrating affinity (what he really believes is another matter). Remember his training: He’s a former intelligence officer. With Trump, it will be even easier to find common ground, since they do share some views about the nature of the world. Trump has expressed his hostility to multilateral organizations such as the European Union, NATO and the World Trade Organization. Putin loathes all those groups. Likewise, both Trump and Putin have embraced nativist nationalists in Europe in the United Kingdom, France, Hungary and Italy.

Sixth, Putin is capable of the bold, unexpected move, sometimes for good and sometimes for bad. Putin has way more autonomy running the Russian government than Trump has in the United States. In convincing us that we needed a presidential summit in September 2013, Putin’s foreign policy adviser, Yuri Ushakov, emphasized this point, stressing that Putin liked the bold gesture if things were going well. Trump should be ready with smart answers to possible grand bargains such as Iranian withdrawal from Syria in return for our withdrawal. That’s a bad deal, even if Putin could deliver on it, since our retreat could allow ISIS to regroup and reemerge as a threat to our allies in the region and even us. But the proposal might sound attractive in a one-on-one talk with Putin, trying to get along. And we know how Trump likes deals.

Seventh, Putin leaves a big impression. Every meeting with him is memorable. As we drove back to Moscow after our breakfast with Putin in 2009, I could tell Obama was still trying to digest the measure of the man. I fear Trump will be easily captivated by Putin’s swagger.

Finally, Putin will probably be late. He made Obama wait for 45 minutes before their meeting in Los Cabos. Kerry wandered Red Square and then chilled at the Ritz-Carlton for several hours before Putin was finally ready to host us at the Kremlin in 2013. Of course, Putin wants to make a good impression with Trump. If he is on time, that might signal his real desire to embrace Trump — and then we should all get a little more worried.

I was supposed to go to one other planned summit between Obama and Putin in September 2013 in Moscow. Our embassy had worked on the details of this two-day meeting for months. But when Putin wouldn’t agree to generate a substantive agenda, particularly on Syria and arms control, we started to doubt the value of the meeting. Putin’s decision to grant former National Security Agency contractor Edward Snowden asylum that summer sealed the deal. We could not have Obama standing next to Putin pretending like everything was business as usual after such a provocative act. Obama canceled the summit. I delivered the news to the Kremlin, and they were genuinely upset with our acceptance and then refusal of their invitation to come to Moscow.

But sometimes not talking — not showing up — is the right diplomatic move. Maybe there’s a lesson in this story for Trump?

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