On Monday, President Trump will become the fourth consecutive American President to hold a summit meeting with the Russian President, Vladimir Putin. Trump’s three predecessors each found Putin a challenge, starting out with high hopes only to have their dealings end in frustration and mutual recriminations. Will Trump fare differently?

This President is betting on it. He personally insisted on the risky summit, despite advisers’ cautions and the long shadow of Russia’s meddling in the 2016 election on his behalf. Beyond meeting Putin, it’s unclear what Trump hopes to establish in Helsinki, and the two sides have not agreed on any of the “deliverables” that are traditionally negotiated in advance of such a session. “The President has determined that now is the time for direct communication between himself and President Putin,” Trump’s Ambassador to Moscow, Jon Huntsman, told reporters before the trip. “And that’s the way he’s proceeding.”

From the start of Trump’s Presidency, the prospect of such a meeting has alarmed and worried many of America’s top Russia-watchers, especially given Putin’s long record, over nearly two decades, of first raising, then dashing, the hopes of Bill Clinton, George W. Bush, and Barack Obama—hopes that personal encounters might produce a stable and new long-term foundation for the two former Cold War adversaries. In the end, they all ended up in what a longtime senior U.S. official, who advised all three Presidents, told me were “honorable failures.” In fact, it was in an angry, private conversation on the sidelines of a world-leader summit in September, 2016, in China, that Obama warned Putin to knock off the election hacking.

So what will be the outcome of this summit that has no agenda and is of Trump’s making, amid a renewed hue and cry over Moscow’s interference in the 2016 U.S. election? I asked an array of Washington’s top Russia hands, who have advised every American President since Ronald Reagan on superpower summitry, what to expect. Many of the sixteen former senior U.S. officials I consulted—who included a former national-security adviser, four former U.S. Ambassadors to Russia, and two former Deputy Secretaries of State—have sat in the room with Putin and his American interlocutors during the past eighteen years, and they are well aware of the formidable combination of extensive preparation and historical grievance that Putin brings to the bargaining table.

Trump, of course, is famous for not caring much about the expertise of the government he now heads. Had he consulted with those who have made it their job to understand Russia during the past several decades, here’s some of what he would have heard.

1. What are the best and worst potential outcomes of the Helsinki summit?

Best Outcome

“We need to think in terms of best possible outcome, because the best outcome is not available—meaning Trump will not press him on meddling in ours and other elections. Having Putin understand that we can use cyber to expose things he does not want exposed if Russia persists is not in the cards. Neither is the grand bargain on Crimea and Ukraine for Russia containing Iran in Syria. Leaving aside the morality of such a bargain, it is also not in the cards. Putin has his own version of the Brezhnev Doctrine: what is his or can be used to lever others (e.g., frozen conflicts) is irreversible and he is not going to trade what he already has.”—Dennis Ross, a top State Department official for George H. W. Bush during the collapse of the Soviet Union

“Trump’s closest advisers (especially national-security adviser John Bolton) can rein him in from trying to buddy-buddy stuff with Putin. Also, keep him from even hinting that Crimea annexation is O.K. and/or we’ll let bygones be bygones. And finally undo some of the damage he’s done at the G7 and NATO summits. That’s for what Trump must not do. What he might do is scope out whether Putin might go for extension of New Start before it expires in 2021 (but remember: all Trump knows about New Start is that it’s an Obama thing and therefore poison). The treaty is heading for the ash heap of history—which could mean that arms control is kaput.”—Strobe Talbott, the Deputy Secretary of State for Bill Clinton

“The two leaders establish a working relationship, there is no blow-up or love-fest, there are no major concessions, and the two leaders agree on a few very modest steps to begin to restore relations between the two countries (e.g. military-related confidence-building measures, commitment not to interfere in each other’s elections, a commitment from Putin to respect the sovereignty and territorial integrity of the Baltic States within their current borders).”—Stephen Hadley, the national-security adviser for George W. Bush

“Best outcome is Hippocratic—do no more practical harm in indulging Putin and his aggressiveness. The danger is that Trump will fall prey to one of two illusions. First is that personal rapport can transform relationship. Second is that grand bargains are within reach. Putin, a trained professional, will play to his ego and his illusions.”—William Burns, the U.S. Ambassador to Russia under George W. Bush and the Deputy Secretary of State for Barack Obama

“Nothing of significance is said or done.”—Sarah Mendelson, the U.S. Ambassador to the U.N. Economic and Social Council under Obama, and a longtime Russia expert

Worst Outcome

"Either a blow-up between the two leaders that further poisons the relationship between the two countries or major U.S. concessions on key substantive issues (e.g. Crimea, Syria, European security). I do not expect either.”—Stephen Hadley

2. Is there any historical parallel to this summit?

“Like the Reykjavik summit in 1986 between Ronald Reagan and Mikhail Gorbachev, this will be a come-as-you-are, rather free-wheeling session. Then, it was due to the short, ten-day interval between the summit’s announcement and happening. Now it’ll be due to the unwillingness, or inability, of the President to focus on anything for more than ten minutes.”—Kenneth Adelman, the chief arms-control negotiator for Ronald Reagan

“Nope. It would be an insult to JFK to say that the Vienna summit with Nikita Khrushchev was anything like this. JFK committed a rookie error. Trump has a plan—if you can call it that—to reorient the U.S. to leaders that he has an affinity for and countries that he’d like ours to become.”—Strobe Talbott

“Not that I can think of. Perhaps the Trump-Kim meeting, but even that one had more time for planning.”—Thomas Graham, a senior National Security Council official for Russia during the George W. Bush Administration

“I’ve been involved with most US-Russian high-level encounters since VP Bush’s first meeting with Gorbachev in 1985. There is no historical precedent that I know of for such a potentially high-stakes US-Russia meeting to take place with so little advance preparation, and with such a dark cloud of suspicion and uncertainty hanging over it. We are really in uncharted waters here.”—John Beyrle, a career diplomat who served as a U.S. Ambassador to Russia for George W. Bush and Barack Obama

“No. I cannot remember a US-Russian or US-Soviet summit at which the president of the United States was so eager to befriend a Kremlin ruler.”—Michael McFaul, a U.S. Ambassador to Russia for Barack Obama, and the author of the book “From Cold War to Hot Peace: An American Ambassador in Putin's Russia”