The impending Trump-Putin summit gives Atlanticists the jitters. Meeting the leader of the free world should be a reward for good behavior; the Russian leader has done nothing to deserve it. On current form, a showy deal—a new Yalta, some fear—could trade security (and allies) for nebulous pledges.

Putting those gloomy thoughts aside, ponder possible positive outcomes. First would be clear messaging. President Trump could plausibly tell Vladimir Putin that any interference in the U.S. midterm elections will result in much harsher sanctions. Even Mr. Trump’s most diehard supporters do not actively welcome the idea of foreign interference in American politics.

The U.S. leader should also tell his Russian counterpart to forget hopes of a grand bargain, over Ukraine or anything else. Sanctions will stay while Crimea remains occupied. Russia must observe the Minsk deal. Any other improvement in U.S.-Russia relations will come slowly, from small steps and confidence-building measures.

Mr. Trump should underline that despite rows with allies over trade and defense spending, the transatlantic relationship remains strong. The Kremlin’s divide-and-rule tactics may have been effective so far. But there are limits.

Next, Mr. Trump should flatter Mr. Putin. For all its economic, political, and social weaknesses, Russia is still a cryptographic, cultural, nuclear, space, sporting, and geographic superpower. On all these fronts, there is plenty to talk about. International talks on global internet governance need a boost. Russia’s puny digital industries would benefit from a rules-based international order. Mr. Trump could see if Mr. Putin shares his concerns about China’s ambitions towards internet dominance. Digital arms-control talks could produce benefits for both sides, for example in agreeing to a “hands-off” approach to missile-defense systems.

On that subject, Mr. Trump could also remind Mr. Putin that Russia, as the weaker power, has the most to lose from an arms race, and the most to gain from a return to arms-control agreements. These have frayed badly in recent years, for which Russia is largely to blame. But if the U.S. could talk to Leonid Brezhnev’s Kremlin about nuclear stability, it can do the same with Mr. Putin’s rackety regime.

An immediate priority would be deconfliction—ensuring through military-to-military channels that Russia and the West do not start shooting each other by accident. This has worked surprisingly well in Syria. There is scope for a similar approach in the Baltic and Black seas, along with transparency on military exercises: both their size and their nature. Another useful topic would be space safety. A joint U.S.-Russian mission to research ways of zapping or trapping satellite-killing space junk would be a nice trophy to take away from the summit.

On the ground, Mr. Trump could sound out Mr. Putin’s views on the increasingly militarized Arctic region. He could point out that Russia’s short-term advantage in the high North would not survive heavy investment by the U.S. (and China). So it would be better to set out some rules now, than have a trial of strength later. He might also remind Mr. Putin that Russian meddling in the western Balkans is destructive and pointless.

To put some icing on the cake, Mr. Trump should also note that Russian culture deserves greater appreciation in the U.S., and suggest a year-long, coast-to-coast festival of art, ballet, literature, and music in 2020. This would neatly defang the Kremlin’s attempt to demonize the West as Russophobic. It would also give an opportunity to push Mr. Putin to lift the absurd “foreign agents” law, which stupidly hampers the promotion of foreign culture in Russia.

Such an agenda would not spook U.S. allies. It might even do some good.