Nuclear proliferation appears to weigh heavily on U.S. President Donald Trump’s mind. Standing next to his Russian counterpart, Vladimir Putin, in Helsinki last month, Trump said ominously that it’s “probably the most important thing that we can be working on.” Since then, Trump has proposed dramatically to negotiate denuclearization with Iran — after threatening the country with “consequences the likes of which few throughout history have ever suffered before” — and even floated the idea of a second meeting with North Korean dictator Kim Jong Un with the goal of dismantling Pyongyang’s nuclear arsenal.

For someone whose projection of power derives so intensely from online networks, Trump is surprisingly old-fashioned.

During the 1964 presidential campaign, President Lyndon Johnson aired a spot deemed so controversial than it never ran a second time. As an innocent, young girl picked petals off a daisy in the park, her voice was drowned out slowly by a launch countdown. Then, narrating against the backdrop of a mushroom cloud, Johnson proclaimed: “We must either love each other, or we must die.” His Republican opponent, Barry Goldwater — the implicit warmonger who was not even mentioned by name — lost by an overwhelming margin.

But the more contemporary battlefield of cyberspace merited not one single mention in Trump's remarks alongside Putin in Finland. Unless you count the infamous Democratic National Committee server, that is, which he referenced nine times. While Trump obsesses about politics, the U.S. is exposed to great danger.

Drawing a direct comparison to 9/11, Dan Coats, the director of national intelligence, has warned that America’s “digital infrastructure … is literally under attack.” He fingered Russia as the “most aggressive foreign actor” and awarded dishonorable mentions to China, Iran and North Korea.

Trump then chose to accept Putin’s denials of Russian interference over the assessment of his intelligence chiefs. His subsequent reversal was unpersuasive.

There’s a problem with Trump’s stale frame of reference. The harnessed atom still holds the capacity to wreak mass destruction. But the doctrine of mutually assured deterrence has ensured that nuclear weapons have not been deployed in battle since the World War II raid on Nagasaki, Japan. Fears of dirty bombs falling into terrorist hands have, thankfully, not yet become a reality. Vigilance is imperative, but even the craziest dictators have plenty of incentives to keep their nukes under lock and key.

Trump has prioritized nuclear arms control nonetheless. It must fit his perception of what the leader of a superpower must do. Maybe he believes that a nonproliferation deal is the key to “making America great again.” But there’s a catch: The cunning crew at the focus of Trump’s anti-nuclear push — Putin, North Korean strongman Kim Jong Un, Iranian Supreme Leader Ali Khamenei, Chinese President Xi Jinping — are the exact same cast of characters whom Coats accused of cyber-targeting U.S. government, military, academic and financial institutions. Even if Trump gets lucky and reduces the world’s nuclear footprint, he’s ignoring a no less potent weapon in the hands of America’s sworn adversaries.

The truth is that when it comes to cyber, Trump gives the impression of being more frightened by the capabilities of his own government than the Russians. To Trump, Putin is simply a “good competitor” — something Trump the businessman considers a compliment — but the probe being conducted by special counsel Robert Mueller, who indicted 12 Russian operatives for meddling in the 2016 election, is “ridiculous.”

In Trump’s thinking, Mueller’s investigation of Russian meddling into the U.S. democratic process — not proven Russian cyber-tampering itself — is a nonconventional danger on the magnitude of nuclear winter. But Kremlin psy-ops to tilt the 2016 ballot are likely to be the tip of this iceberg, as U.S. authorities brace themselves for a repeat performance during the upcoming midterms.

This is no longer science fiction. With more and more of the world’s commerce, security and even physical health delegated to technological platforms, nations (and individuals) are becoming vulnerable increasingly to the implements of cyberwarfare. Examples abound in the Middle East, Asia and elsewhere.

Much has — and will — be done in the realm of cyber defense. It’s a cat-and-mouse game, and the hostiles are not the only ones with tricks up their sleeves. But Trump’s dismissive attitude toward hacking as something that “everybody does” puts America behind a massive curve. Nonproliferation is a worthy goal, but it cannot alone provide the kind of blanket security it once promised if the trolls of the internet are left free to roam.

Shalom Lipner is nonresident senior fellow of the Center for Middle East Policy at the Brookings Institution. From 1990 to 2016, he served seven consecutive premiers at the Prime Minister’s Office in Jerusalem. You can follow him on Twitter at @ShalomLipner.