Conceived in the depths of the Cold War by President Dwight Eisenhower and pressed forward by President George H.W. Bush to promote international stability after the fall of Communism in Eastern Europe, the Open Skies Treaty allows the United States, Russia and other nations to send unarmed surveillance flights over one another’s territories to monitor military buildups or warnings of a surprise attack.

It’s a common-sense arms control agreement that was unanimously ratified by the Senate in 1993 and that has caused no major controversies among its 34 signatories since it took effect in 2002. It has been especially useful to the United States and Europe in monitoring Russian military operations in its war against Ukraine.

So it looks as if President Trump will withdraw from it.

While Mr. Trump has discarded other arms control treaties that helped stabilize the world, lawmakers and experts have expressed shock that he might pull out of so productive an arrangement as the Open Skies Treaty. They fear the only beneficiary would be Russia.

Last year, while he was defense secretary, James Mattis said it was in America’s “best interest” to stay in the treaty.