President Trump left on his second foreign trip today, first stop Poland. But all eyes will be focused on him later this week when he meets in Germany for the first time with Russia’s meddling President Vladimir Putin.

Both men will attend the G-20 meeting in Hamburg. Their first encounter was just to be a conversation on the economic summit’s fringes. But late last week it was elevated to a full-blown bilateral get-together. Watch the body language in that photo-op!

Trump’s national security adviser H.R. McMaster says there is no specific agenda for the two men. If that’s true, which it isn’t, it would be the first such high-level meeting for which aides did not discuss in advance acceptable topics.

Here’s why McMaster claims the agenda will be whatever Trump wants to talk about and, gosh, who knows what that might be: If the adviser said Trump will demand an accounting of Russian hacking or meddling in the 2016 election, the stakes would become astronomical. If McMaster’s discussion topics did not include meddling, that would be the story all this week.

The stakes are still high for Trump. He performed well on his first foreign trek to four countries in May. He successfully resisted the Twitter devil whispering in his ear to tell Prime Minister so-and-so to put a sock in it.

Of course, media will find some Trump gaffe to share widely, which they failed to do when President Obama got his own country’s national motto wrong in Indonesia or revealed that Austrians speak Austrian, when they really speak German.

In May, Trump pushed NATO leaders to boost defense spending to the alliance’s promised 2% of GDP level so their mutual defense could become more effective. But he didn’t specifically pledge to follow Article 5, the “attack-on-one-of-us-is-an-attack-on-all-of-us” one.

Trump’s first stop is Warsaw, a staunch NATO ally that Obama undercut by abandoning a missile defense network. There, the U.S. president will also meet with Baltic leaders, where the American military is still doing joint exercises as a show-of-force against the annex-minded Putin. Trump will hail the arrival in Poland of the first U.S. LNG exports.

Putin is maneuvering to split NATO, feed suspicions about this loud-mouthed American and his commitments, reassert Russian hegemony in Eastern Europe. And feed European dependence on Russian oil and gas.

Trump has plenty to discuss with the Russian leader, including Moscow’s half-hearted efforts to combat ISIS in Syria while, oops, helping Syrians fight anti-Assad forces supported by the U.S. Trump may remind Putin to remind the Syrian leader about the American’s threat should he use chemical weapons again. Trump could seek help reining in North Korea.

The economic sanctions on Russia for annexing Crimea and fomenting rebellion in eastern Ukraine have accomplished nothing, but the New York deal-maker can’t politically ease them. The pair will come out with a joint statement, embellished later by unidentified aides for audiences back home, emphasizing a few things they agree on–the fight against terrorism, for instance.

The most important result of the meeting is likely to be invisible, as each man personally sizes up the other. It’s natural. But as smart as these leaders think they are, such personal impressions can lead them astray. After Russian leader Nikita Khrushchev first met young John F. Kennedy in Vienna in 1960, he knew the new American president was a pushover.

The Russian dispatched nuclear-armed missiles to America’s backyard. And the result was the Cuban missile crisis when the Cold War came the closest ever to Armageddon.