Where do we go from here? That’s the question many are asking after President Trump abruptly canceled military strikes he ordered against Iran in retaliation for Thursday’s downing of an American surveillance drone in the Persian Gulf. The president’s decision contained hostilities — at least for the moment. But it left Iranian-American tensions high, underlying problems unresolved and critics wondering whether Trump has a viable exit strategy.

The diplomatic history of another aerial intelligence mission gone wrong suggests that plausible deniability offers an imperfect but effective way out of the standoff — if both U.S. and Iranian officials choose to follow it.

In 1975, top U.S. officials huddled inside the White House to decide what to say in response to as-yet-unconfirmed reports that an American ship, the Glomar Explorer, was at the center of a CIA operation to raise a sunken Soviet submarine containing nuclear missiles and code equipment from the bottom of the Pacific Ocean. The reports were true, but officials didn’t want to confirm them for fear the news would scuttle Soviet-American detente, perhaps even triggering a Soviet military response.

“I go back to the U-2,” then-CIA Director William Colby told the gathered officials as they contemplated what to do next. He didn’t need to explain much beyond that: Like foreign policymakers today, the high officials assembled in the White House that day could easily recite the basics of 1960’s U-2 incident. They knew that Soviet air defense downed an American U-2 spy plane piloted by Francis Gary Powers on the eve of a scheduled summit meeting in Paris between Soviet premier Nikita Khrushchev and American president Dwight Eisenhower. They also knew that the incident ruined the meeting, the first between Soviet and American heads of state in five years, reigniting Cold War tensions after a brief but promising thaw.

In sum, they knew what we still know today: that the shoot-down of the U-2 — a precursor, it’s worth noting, to the RQ-4 Global Hawk drone downed last week by Iran’s Islamic Revolutionary Guard Corps — resulted in international conflict and that neither Khrushchev nor Eisenhower had the ability to change things.

But Colby, who arrived at the 1975 White House meeting carrying a copy of Khrushchev’s newly published memoirs, pointed out some telling details others might have forgotten. In addition to denouncing the U-2 incursion of Soviet airspace, the blustery Khrushchev also had suggested that anti-Soviet “militarists” within the U.S. government might have launched Powers’s U-2 overflight without President Eisenhower’s authorization. That is, Khrushchev, in an apparent effort to save the summit, provided his American counterpart with a face-saving out.

Had Eisenhower followed Khrushchev’s lead, they might have kept the peace process moving forward. But he didn’t. Instead, Eisenhower publicly acknowledged that he had authorized Powers’s ill-fated mission, and his admission stripped away any pretense that rogue U.S. officials had acted without presidential permission.

Now it was Khrushchev with egg on his face. To save the summit, he demanded it open with an apology from the president for violating Soviet sovereignty. Eisenhower refused, rose from his seat and led the U.S. delegation out of the meeting. Years of intense superpower rivalry followed.

That outcome, Colby explained in 1975, was why U.S. spokespersons should “neither confirm nor deny” — wordplay that would become known as “the Glomar response” — the Glomar reports. Were Gerald Ford, the president at the time, to repeat Eisenhower’s mistake of confirming a clandestine activity, Colby suggested, Soviet premier Leonid Brezhnev could be compelled to take some sort of face-saving retaliatory action against the United States. Such a move would jeopardize detente and might even spark a broader conflict. “I think we should not put the Soviet Union under such pressure to respond,” Colby said.

Colby’s advice prevailed. U.S. officials kept mum, and it would be years before the government officially confirmed Glomar’s existence. And, significantly, the Soviets played dumb as well. Although Soviet officials complained privately about U.S. actions, they never addressed the published reports.

Plausible deniability sustained detente. The superpowers’ conspiracy of silence acted as a face-saving device that avoided the sort of public posturing that had led to flare-ups in the past. “Glomar,” unlike the U-2, “never became the subject of international acrimony,” Colby boasted years afterward. Even Eisenhower eventually agreed about the importance of this tactic, conceding years after the U-2 incident, “If I had to do it all over again, we would have kept our mouths shut.”

Could President Trump have drawn the same conclusions? It is unlikely he is modeling his response after Colby’s; Trump does not appear to be a keen student of history. He probably wasn’t aware of the fact that he sounded very much like Khrushchev on Thursday, when he suggested that the drone shoot-down might have been a mistake. A serious mistake, to be sure, but one made by some unknown person or people — a junior officer, perhaps — within Iran’s Islamic Revolutionary Guard Corps without authorization from above.

“I’m not just talking about the country made a mistake. I’m talking about somebody under the command of that country made a mistake,” Trump said at the White House. “I find it hard to believe it was intentional” on the part of Iran’s top officials. Over the weekend, he also extended further olive branches, including thanking Iranian officials for not shooting down an American military plane with personnel aboard.

It remains to be seen whether he’s serious about finding a peaceful solution or how Iranian leaders will respond.

But the diplomatic history of the U-2 and Glomar incidents suggests that if they seek compromise, if Trump replies in kind and if both sides agree to hold their tongues, the maintenance of plausible deniability can promote diplomatic solutions, especially in a case like this where facts are in dispute. Allowing for plausible deniability prevents each side from facing pressure from within to respond in a bellicose manner to save face and demonstrate toughness.

To be sure, the U-2 and drone incidents are incomparable in many respects. Whereas Powers’s U-2 operated deep within Soviet territory, for instance, Iranian and U.S. officials offer conflicting accounts as to whether the unmanned RQ-4 Global Hawk violated Iranian airspace. American and Iranian negotiators are less familiar, and arguably less trustful, of one another than American and Soviet diplomats were. There is even some question as to whether they have open lines of communication. And it is not at all clear that Washington and Tehran share the same objectives.

However, those differences themselves suggest that the facade of deniability might work to jumpstart the dialogue. But only if American and Iranian leaders don’t mind sacrificing the truth for a grander purpose, and if they follow the lessons Colby learned from the U-2 affair.