Many Americans might not know it, or perhaps just don’t want to think about it, but the nation’s entire nuclear arsenal can be launched by one person — the president — at any time, for any reason (or no reason), with no input from anyone else. The danger of this situation is especially clear now, with a president who demonstrates his instability daily. Really, it’s an unacceptable situation no matter who is president.

“Presidents, like all of us, make mistakes. They are only human,” writes former U.S. Defense Secretary William Perry, co-author of a new book about the nuclear arms race. It argues that it’s past time to fundamentally restructure the way America’s nuclear defense system is set up.

Perry, defense secretary under the Clinton administration, and Tom Z. Collina, director of policy at Ploughshares Fund, are co-authors of the new book, “The Button: The New Nuclear Arms Race and Presidential Power from Truman to Trump.” In a recent New York Times piece echoing themes from the book, they argue that the world has been lucky not to have yet blundered into a civilization-ending nuclear war due to a presidential mistake, and that safeguards to prevent it should be put in place immediately.

“It is time to retire the nuclear button,” they write. “No one should have the unchecked power to destroy the world.”

The current system of total presidential control began under the first president of the nuclear age, Harry Truman, out of fear that overzealous generals might use this terrifying new weapon unnecessarily. Nuclear authority was vested in the president alone on the rationale that seconds would count during a nuclear attack and there wouldn’t be time to consult Congress about striking back.

That rationale, Perry and Collina argue, isn’t true today. The advent of submarine-based missiles, capable of retaliatory strikes weeks or even months after an attack, renders surprise nuclear assault on America strategically useless. Fear of mutually assured destruction kept the U.S. and the Soviet Union in check for decades and still girds today’s nuclear powers.

But even a momentary lapse in judgment by a sitting president could topple that balance, with apocalyptic results.

The authors’ suggestions for avoiding this include an ironclad U.S. policy against launching a nuclear first strike; a designated group from Congress that must agree to any nuclear launch; and retiring all land-based (as opposed to submarine-based) missiles — thus removing that tempting target for a would-be attacker, ensuring the president isn’t forced into “a quick ‘use-them-or-lose-them’ decision.”

America has been reminded these past three years that our system of democracy doesn’t necessarily guarantee selection of a stable and responsible president — and even if it did, all humans make mistakes. A system that conceivably could allow one human’s mistake to end civilization is a system that must be changed.

— The St. Louis Post-Dispatch