The accidental missile alert in Hawaii earlier this month made real for 38 terrifying minutes the vague, low-level dread that permeates American life today: Nuclear war seems closer and more real than it has in a generation. Even the pope—not exactly a fear-monger—said last week that the world now stood at “the very limit.”

That existential fear was affirmed today by the organization of nuclear scientists who have spent seven decades trying to turn humanity away from nuclear weapons: The Bulletin of Atomic Scientists moved its Doomsday Clock 30 seconds closer to “midnight,” an unofficial barometer of how close the world stands to a man-made catastrophe. It now stands two minutes away.

"To call the situation dire is to understate the danger," said Rachel Bronson, the head of the Bulletin, at the National Press Club in Washington, DC, on Thursday, announcing the clock's new setting.

The clock dates back to 1947, when the scientists who participated in the Manhattan Project wanted to create a mechanism to warn of escalating global tensions and the danger of global Armageddon. The iconic stylized timepiece has since become the global arbiter of dread—or hope. It aims to answer two questions: Is the future of civilization safer or at greater risk than it was last year? And how does today's risk compare to the risks we've experienced over the last 71 years?

The graphical clock started at seven minutes to midnight, its two-dozen changes since marking the shifting tensions of the Cold War. Its “peacetime” rating peaked in 1991 at 17 minutes to midnight, as the Soviet Union broke apart. It has gradually ticked darker ever since, first as nuclear weapons proliferated to countries like India and Pakistan, and then as it began to factor in other global threats, like climate change.

Last year, for the first time, it ticked forward a half-minute, reflecting the rise of nationalism and the threat to the post-war international order, as well as President Donald Trump’s troubling supportive comments about the appeal of nuclear weapons, and his climate change skepticism.

At the time, he’d been president only a few days; there was little track record to measure his actions versus his campaign rhetoric. But as Bronson told me last month, “Many of our fears played themselves out in 2017… A lot of our concerns were really borne out.”

Today’s movement of the Doomsday Clock—announced live in a webcast—was yet another sign that the world stands on a precipice perhaps unparalleled in the modern era. It hasn’t sat this close to midnight since 1953, a few months after the United States and Russia tested their first thermonuclear bombs.

Last week, as he started a trip to South America, Pope Francis handed out to reporters aboard his Alitalia plane a photo from 1945 that depicted a Japanese boy carrying his dead brother in the hours after the US bombing of Nagasaki, a nuclear weapon roughly equivalent to what US intelligence believes North Korea possesses. The Pope cautioned his travel companions, “I am really afraid of this. One accident is enough to precipitate things.”

The Pope’s comments reflected, whether intentionally or not, the strong sense of the presidents who lived through the danger of the Cold War: They rarely feared the superpowers intentionally launching global general thermonuclear war. Instead, what men like Dwight Eisenhower, John F. Kennedy, and Ronald Reagan feared was a rapid escalation through miscommunications, misunderstandings, and miscalculations that resulted in the two countries stumbling into a war neither intended.

As it turns out, if there’s one critical geopolitical lesson of the Cold War—one that should be impressed on every commander-in-chief in turn—it’s that nuclear war is actually hard to avoid.