The revelation that President Trump remains unconvinced of NATO’s value to U.S. security, arguing instead that it is an unnecessary drain on the country’s resources, has renewed doubts both in Washington and around the world regarding the survival of the alliance.

President Trump is not the first sitting president to critique NATO. Since the beginning of the alliance, many presidents have similarly expressed frustration over the costs of the United States’s European commitment. From the moment he took office in 1953, President Dwight Eisenhower, NATO’s first Supreme Allied Commander, repeatedly called for greater European defense efforts to reduce the United States’s burden.

But President Trump has taken these criticisms further. By declaring the alliance obsolete and demanding a complete U.S. withdrawal, Trump is advancing a position no U.S. president has ever taken. Eisenhower, though concerned about costs, never wavered in his commitment to NATO, even though it risked nuclear war with the Soviet Union. Why? Because Eisenhower understood the deterrent-value of NATO: Any invasion of Europe automatically meant war with the United States, thus reducing the Soviets' incentive to attack.