Gov. Jerry Brown, who has seen much to worry about in his five decades in public office, said recently that he had a particularly heavy concern: the nation's obliviousness to how close it is to nuclear catastrophe.
"There is virtually no conversation about this, and it is damned dangerous," Brown said to journalists and politicians in Philadelphia last month, after steering the conversation to the threat of nuclear warheads exploding. "We really ought to wake up."
Soon, the public did wake up. Donald Trump saw to it.
Trump has suggested America use nuclear weapons to bomb Islamic State. He has proposed that Japan and maybe even Saudi Arabia build their own arsenals. And he may have weakened the deterrent effect of nuclear bombs in Europe by suggesting a Trump administration would not come to the aid of NATO members who owe the alliance money.
But the public most took notice, perhaps, when MSNBC host Joe Scarborough told an anecdote about Trump asking a foreign policy expert three times during a briefing why the U.S. doesn't use its nuclear weapons. Trump's campaign denies any such query took place.
Not since Ronald Reagan's reelection at the tail end of the Cold War have nuclear weapons played so big in a presidential race. Historians have to reach back even further, to decades before Reagan, to find a nominee who has talked about nuclear war as loosely as Trump does.
Until Trump came along, voters had largely shifted their worries elsewhere, away from the sobering reality that nuclear warheads can pulverize entire cities in an instant, that they are so powerful that merely possessing them is a deterrent to war, and that presidents can order, on their own, that a nuclear weapon be launched.
"It's been shock therapy for the American public," said Joseph Cirincione, president of the Ploughshares Fund, which promotes nuclear disarmament. "Up until last month, most Americans did not even know a president could launch a nuclear war on their own authority."
Regardless, Trump has plunged into an issue presidential candidates gently sidestepped for years. U.S. policy for when and how nuclear arms should be deployed has been one of the rare points of bipartisan foreign policy agreement. Yet it doesn't fit neatly into Trump's unique ideology, which is driven by challenging existing orthodoxy on everything.
This is one corner of policy, though, where his vow to shake things up is not so much energizing voters as unnerving them. On the questions of national security and temperament, voter confidence in Trump lags far behind that of rival Hillary Clinton.
One of Clinton's most effective lines on the stump now is asking whether someone who can be so easily baited by a tweet should have his finger on the nuclear button.
Amid an outpouring of alarm from national security experts — including dozens who served at the highest levels of Republican administrations — even many die-hard Trump supporters admit they are rattled by the idea.
During a recent focus group of women in Arizona and Ohio, the nuclear issue gave pause to voters otherwise committed to Trump. A staunchly conservative woman from Phoenix said she was hopeful that a President Trump would not be empowered to "just hit the button" at will. "I'd really like to think that there are more controls," she said.
The problem, as Americans are fast learning, is that there really are not that many controls.
"You get into some dangerous hypotheticals of what it would look like if Donald Trump gave an order" disputed by the military, said John Noonan, a GOP security advisor.
He would know. Noonan is a former Air Force launch officer, a job in which he held the codes for launching intercontinental nuclear missiles.
"The question is whether the nuclear infrastructure is robust enough to survive instability at top. I think it is. But this also places unnecessary stress on the military.
"The best thing American people can do is just make sure Donald Trump is never elected president."
Noonan says Trump has unnecessarily panicked the public, triggering worries that have been latent for decades.
"For my parents and grandparents, there was always a very real threat that at any moment a crisis in a remote region of the world could escalate into a massive nuke attack in the United States," he said. "I grew up not worrying about that. Trump has reintroduced that specter onto the national scene."
Other scholars of the nuclear triad say the jolt Trump has given the electorate could ultimately prove useful — even if many of them, like Noonan, want Trump nowhere near the nuclear arsenal.
"His comments have forced us to reckon with the fact that our current nuclear posture remains unnecessarily risky," said Kingston Reif, director for Disarmament and Threat Reduction Policy at the Arms Control Assn., a Washington think tank.
Nuclear weapons have emerged as a focal point in the presidential race as President Obama contemplates adding new safeguards into the rules governing their use. Options the president is mulling include banning America from striking first with a nuclear weapon, which current policy allows under certain extreme circumstances.
"There are a lot of question about what our nuclear policy should be, what we should spend the money on, what the president's power should be with regard to use of the weapons," said James Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment. "The fact that these things are not being discussed is a point of weakness."
"If Trump's comments spark a sensible public conversation, that may be a silver lining," he said. "But it is clearly not the optimal way to spark this discussion."
Brown is looking for a bigger conversation. He recently wrote a sobering review in the New York Review of Books of "My Journey at the Nuclear Brink" by former U.S. Defense Secretary William Perry, who has convinced Brown the world is closer to a nuclear catastrophe than even during the Cold War.
In a phone interview, Brown vividly lays out a scenario Perry warns about in which terrorists could smuggle a crude nuclear device into the center of Washington and use it to wipe out the president, key Cabinet members, most of Congress and tens of thousands of people — setting off mass panic and descending the nation into chaos.
"The only way people talk about [nuclear weapons] is as if Trump might get his hand on the button," Brown said. "Whether he does or not, we have these catastrophic dangers lurking out there. And leaders that should be worrying about it are sleepwalking."
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