Bad news from the U.S. Defense Intelligence Agency: North Korea has developed a “miniaturized nuclear warhead that can fit inside its missiles.”

The Hermit Kingdom is not alone in its nuclear pursuits. Russia and China have also committed to exploring new weapons capabilities, and Iran still harbors nuclear aspirations. In the United States, however, attempts to modernize our nuclear arsenal face tremendous resistance.

The scale, scope and capacity of the Russian and Chinese nuclear modernization programs far outstrip current U.S. efforts. Failing to modernize our aging warheads and platforms carries tremendous risk that goes well beyond those posed by not “keeping up with the Joneses.”

U.S. nuclear weapons are old. The warheads are based on 1970s designs, and they have not been physically tested in a quarter of a century. The nuclear triad of bombers, submarines, and long-range missiles is long in the tooth, as well. The Minuteman long-range missiles were deployed in the 1970s.

B-52 bombers, introduced in the 1950s, are so old that occasionally a grandson jockeys the same tail number that his grandfather flew. Even our newest systems, the Ohio-class ballistic missile submarines and B-2 bombers, are more than two decades old.

The nuclear triad is the bedrock of U.S. strategic deterrence and a core component of U.S. security assurances to over 30 allies around the world. It must be modernized — regardless of the fate of the New Strategic Arms Reduction Treaty, also known as New START. The centerpiece of the Obama administration’s failed Russian “reset” policy, New START has not served the strategic security interests of the United States.

It called for — and delivered — disproportionate reductions to the U.S. nuclear weapons arsenal. Moreover, the Russians have flagrantly violated the spirit of the treaty, deploying more than 200 nuclear warheads morethan the treaty permits. (Nothing new there. Russia is also violating several other arms control agreements, including the Intermediate-Range Nuclear Forces Treaty.)

Former officials of the Obama administration, who had a hand in the 2010 Nuclear Posture Review, now recognize that the strategic environment has become significantly more dangerous since that review was concluded. The review was based on two questionable assumptions: that Russia was no longer a threat and that Russia (or any other country, for that matter) would not be a major adversary in the future.

But much has changed since those calculations were made. Russia, for example, has annexed Crimea, sent troops into Ukraine and propped up Bashar Assad in Syria. China has become more aggressive and belligerent in the South China Sea. And then there’s North Korea. No one can know the future, of course. International developments have a way of taking the United States by surprise. And this unpredictability is precisely why the U.S. must maintain a credible, viable and robust nuclear deterrent.

Modernization is essential because the determined efforts of Russia, China and even North Korea leave the United States at risk of losing its competitive edge and thus its strategic deterrent. Both Moscow and Beijing reportedly include nuclear warhead testing as components of their modernization programs. And both are likely pursuing innovative design and development work to create warheads capable of generating special effects, such as enhanced radiation or electromagnetic pulse. Robust modernization programs also mean that their warhead workforce and production facilities remain skilled, capable and agile.

This is another area where the United States risks falling behind. U.S. scientists and nuclear engineers primarily focus their work (and thinking) on warhead maintenance and life extension programs — a different set of skills than actually designing and building new warheads. The former attempts to sustain what is already known, while the latter explores new possibilities and leads to new designs and potential uses — critical things to know if only to know what to defend against.

At present, the U.S. national laboratories are doing little to improve their understanding of foreign nuclear weapon designs. Those limited efforts should be expanded. Not only would it educate the current and upcoming generation of nuclear weapon designers, it would help ensure that the next generation tasked to certify our nuclear stockpile reliable has the experience and know-how of designing, building and testing actual warheads.

It made no sense for the French, British and Americans to remain committed to horse cavalry while the Germans were developing mobile tank warfare. So, today, it makes no sense for the U.S. to remain committed to merely certifying vintage nuclear weapons while our competitors race forward with new research and development efforts.

U.S. nuclear weapons policy must evolve as the nuclear threat evolves. Making changes to the U.S. nuclear posture as the threat environment grows more challenging will ultimately put the United States and its allies in a better strategic position. Congress and the Trump administration must not waver in their support for the U.S. nuclear modernization program.