President Donald Trump has signed a document expressing an intent to withdraw from what must be the least controversial arms-control treaty on the books without consulting the military, the State Department, or the intelligence community—all of which oppose him on this issue.

The accord is the Open Skies Treaty, signed in 1992 by the United States, Russia, and 32 other countries, including 27 of the 29 NATO nations. (The two that haven’t signed are Albania and Montenegro.) It allows member-nations to fly unarmed reconnaissance planes over one another’s territory in order to collect data on military activities.

The idea of an “open skies” treaty dates back to President Dwight Eisenhower, who proposed it in 1955. The Soviet Union rejected the proposal. President George H.W. Bush revived the idea in 1989 as the Cold War was ending, and the new Russian government agreed to negotiate.

Unlike some arms-control treaties, Open Skies has never been the subject of partisan dispute. More than 800 flights have taken place since the treaty went into effect in 2002, many of them crucial to international stability. For instance, Ukraine has invoked the treaty to monitor Russian troop movements along its eastern border, into Russian airspace.

According to three knowledgeable sources, Trump’s move stems from the persistent influence of John Bolton, even one month after he was fired as national security adviser. Bolton had been advocating the pullout for some time. After his dismissal, one of his aides, Tim Morrison, who continues to work on the National Security Council staff, kept pushing it. Finally, sometime last week, Trump signed the document expressing his intent to withdraw from the accord.

Robert O’Brien, Bolton’s replacement, didn’t quite know what to do when he saw the signed document, sources say. There had been no NSC meetings on the subject, no discussions of any sort. The U.S. officials who work on treaty-related issues had just sent a list of the next several planned American overflights to the international commission that sets and mediates the treaty’s rules, restrictions, and data-sharing procedures.

The president’s signature on Bolton’s memo does not, by itself, yank the United States out of Open Skies. Article XV of the treaty states that any nation intending to withdraw must notify the other members “at least six months in advance.” Trump has not given any such notice, nor has any NSC meeting been held to discuss the idea.

Once word got around that Trump had signed Bolton’s memo, lawmakers and even military commanders—who were taken completely by surprise—began to voice opposition. On Monday, New York Rep. Eliot Engel, chairman of the House Foreign Affairs Committee, sent a letter to O’Brien “strongly” urging him not to take “such a reckless action,” noting, “American withdrawal would only benefit Russia and be harmful to our allies’ and partners’ national security interests.” It would also “further undermine America’s reliability as a stable and predictable partner when it comes to European security.”

Defense officials and consultants, some of whom are skeptical of other arms-control accords, agree that a withdrawal from Open Skies would hurt the U.S. and its allies much more than it would hurt Russia.

Engel’s letter was the first public sign that Trump had even considered withdrawing. The next day, U.S. Strategic Command, which operates the overflights (and also controls the nuclear arsenal), tweeted that the command “supports #OpenSkies Treaty by flying peaceful, unarmed flights over 30+ participating countries to observe military forces and activities. This helps build confidence & increase transparency.”

The tweet—which may have seemed random and a bit puzzling to those unaware of the looming controversy—made no mention of Engel’s letter or Trump’s move, but it sent a clear signal that the military officers running the program would oppose a withdrawal.

Officials and consultants in the national security world are flabbergasted by the development. There have been a few concerns about Russia’s compliance with the treaty in recent years, but they have been brief, isolated, and sparked by unusual events. For instance, Russia once restricted flights over its military deployments in Kaliningrad, but that was after Polish planes flew over the small enclave in a very unusual zigzag pattern, angering the Russians by jamming their airspace much longer than expected.*

The State Department issued a report in August, saying it “remains ready to work in good faith with Russia” in resolving the issue. However, Alexandra Bell, a former State Department official and now senior policy director at the Center for Arms Control and Non-Proliferation, told me that the Trump administration “has made no clear efforts to fix this situation.” She added, “This is not just about Russia. The United States also has an obligation to work with the 32 other parties to the agreement, most of whom are allies, who all value and support” the treaty.

A withdrawal from Open Skies would hurt the U.S. and its allies much more than it would hurt Russia.

Bolton has long opposed arms-control treaties—and the very notion of international law—as a matter of principle. He once declared, “It is a big mistake for us to grant any validity to international law even when it may seem in our short-term interest to do so—because, over the long term, the goal of those who think that international law really means anything are those who want to constrain the United States.”

Morrison, the aide who pushed the document onto Trump’s desk even after Bolton was fired, feels the same way. Morrison once worked for Arizona Sen. Jon Kyl. In 2010, as the Republican’s minority whip, Kyl pressured President Barack Obama to increase spending on nuclear weapons by tens of billions of dollars, in exchange for support of the New START treaty that Obama had just signed with Russian President Dmitry Medvedev—and then Kyl voted against the treaty anyway. I once asked a former aide of Kyl (not Morrison) for an explanation. The aide replied, “He just doesn’t like arms control.” Those who know Morrison say he has the same attitude.

(Kyl resigned from the Senate in 2013. New START was ratified, despite his opposition, by a margin of 71–26. The treaty, however, expires in 2021, and Trump has shown no interest in extending it.)

What happens next? Maybe nothing. If the United States government doesn’t submit a formal withdrawal notice (an act that’s usually performed by the secretary of state), the whole issue will go away.

It is quite possible that Trump signed Bolton’s document without having the slightest idea of what the Open Skies Treaty is or how much havoc an American withdrawal would wreak—among diplomats, military officers, and intelligence analysts here and in Europe. It’s also quite possible that he doesn’t care about antagonizing the “Deep State” and the foreign “freeloaders.” He may order his will be done just to spite them all.

Correction, Oct. 9, 2019: An earlier version of this article misstated that Polish planes flew over Kaliningrad in an unusual zigzag pattern. The pattern was not different from what had been arranged ahead of time; it took longer than Russia anticipated.