Remember when Barack Obama stood in Prague in 2009 and called for a world without nuclear weapons? That feels like another planet.

Today, the United States faces an aggressive nuclear peer in Russia, with another antagonist racing towards full peer status in China—while North Korea and others expand their arsenals on the margins. The assumptions that guided policy for decades—stable deterrence, manageable arms control, a world where nukes fade into the background—no longer hold.

We sat down with Brendan Green, Associate Professor of Political Science at the University of Cincinnati and author of The Revolution That Failed: Nuclear Competition, Arms Control, and the Cold War, to unpack what this means.

Some highlights:

* China’s buildup: Beijing is no longer content with a “minimum deterrent.” It’s building a triad to match the U.S. and Russia.

* Russia’s unraveling: Relations are at rock bottom, arms control is dead, and Moscow is leaning on nuclear threats to manage its conventional weakness.

* MAD under pressure: Mutually assured destruction once promised stability. But advances in counterforce, missile defense, and command-and-control raise doubts about whether MAD still holds.

* Allies on edge: If Washington can’t credibly guarantee protection, partners like South Korea, Japan, and Germany may rethink their own nuclear options.

The upshot: nuclear weapons are back at the center of world politics. The U.S. may not need to double its arsenal, but “relatively modest adjustments” in posture—new theater options, modernized warheads, and credible damage-limiting capabilities—could decide whether deterrence holds in the coming decade.

As Green puts it, arms racing isn’t just about warheads. It’s about politics, reassurance, and the credibility of America’s commitments. And in this “new nuclear age,” credibility is what counts.

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