The United States has the world’s most powerful military ever. It spends more on defense than the next seven countries combined and has developed many of the most destructive conventional weapons ever created to ensure that America can address any threat. Congress consistently authorizes investments in innovative technology and weaponry to protect our country and our allies.

We also possess a strong nuclear deterrent. These are insanely destructive weapons with an unparalleled ability to kill and destroy, both instantly and for years afterward from the nuclear fallout. Nuclear weapons should never, ever be used first and new nuclear weapons must not be designed to be more usable.

Yet last year, the Trump Administration came to Congress with just such a request to develop a new “low-yield” nuclear warhead for our submarine-launched ballistic missile, the Trident D5. Congress foolishly authorized the development of this warhead on a party-line vote, but there is still time to correct course. Earlier this year, we introduced the Hold the LYNE Act to prohibit the warhead from being deployed. The House of Representatives is now poised to debate the issue this month as it crafts the annual National Defense Authorization Act.

Calling the proposed warhead “low-yield” is wildly misleading. It is a ploy to obscure the fact that this warhead is a nuclear weapon that has a yield roughly one-third the size of the bomb the U.S. dropped on Hiroshima in 1945, making it 500 times larger than the largest conventional bomb we have. It would have more killing power than would ever be needed for conventional military engagement: one bomb could kill 80,000 people and injure 120,000 if exploded in downtown Washington, D.C.

More importantly, the so-called “low-yield” warhead would be carried on the same submarine-launched missiles that carry high-yield weapons. If we ever launched one of these missiles, our nuclear adversaries would immediately face a “discrimination problem”: they would have to guess within minutes whether the missile carried a single low-yield warhead or several city-destroying ones. We should not bet the possible fate of civilization on the idea that an adversary might wait for the warhead to detonate before deciding on how to counterattack.

Not only is this new weapon dangerous, it is also redundant. The United States deploys more than 100 nuclear gravity bombs in bases owned by five NATO allies. These warheads are “variable-yield” bombs, including low yields. In addition, U.S. bombers can carry long-range cruise missiles that have low-yield options. In short, if we really need a “small” nuke, we already have it. Indeed, no service leaders presented a military requirement for new “low-yield” weapons, which only reinforces the conclusion that their development is simply a misguided Trump administration policy decision.

The debate over low-yield warheads brings back an old, discredited argument: that nuclear war, if it starts small, could be “controlled” and might not morph into all-out nuclear holocaust. Advocates of “limited” nuclear war take advantage of the happy fact that there has never been a nuclear exchange between two atomic states, and thus we do not really know how it would go. They suggest that if one side used a “small” nuclear weapon, the other side would only ever do the same because they would not want to escalate to full-scale war that could mean utter destruction for both sides.

In our view, there is every reason to believe that, once attacked with even one atomic weapon of any size, a nation in shock may assume a full attack was imminent and respond with everything in its arsenal. Expecting a limited response—and risking millions of lives on that guess—is irresponsible and dangerous. Further, it takes the decision about whether we engage in nuclear war out of the hands of the United States and instead puts it into the hands of our adversaries.

Fundamentally, preparing for limited nuclear war is folly. A nuclear weapon is a nuclear weapon, period. As former Defense Secretary Jim Mattis said, “I don’t think there’s any such thing as a tactical nuclear weapon. Any nuclear weapon used at any time is a strategic game changer.”

Using the 2020 NDAA to bar the deployment of new “low-yield” nuclear weapons is just one of the steps we should take to reduce the chances of nuclear war. Another is ensuring that no president has sole authority to start a nuclear war. That’s why we introduced legislation to require Congressional authorization for a nuclear first strike. As well, we should focus our nuclear arsenal on the primary mission—deterrence—and promote stability. A good first step would be for the Trump administration to extend the New START Treaty – which caps Russia and America’s strategic nuclear arsenals in a transparent and verifiable way – for an additional five years.

Until these policies become a reality, it is up to us in Congress to rein in bad ideas that make nuclear miscalculation more likely.

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