In about five years, the United States will not have a single active engineer with actual nuclear weapons testing experience, defined as “a key hand in the design of a warhead that’s in the existing stockpile and who was responsible for that particular design when it was tested back in the early 1990s,” according to Thomas D’Agostino, the Administrator of the National Nuclear Security Administration. This could have significant negative consequences for the future of U.S. national security.

D’Agostino maintains that “In my tenure in this job and however long it’s going to be out into the future, I’m supremely confident that we do not need to test a warhead” (emphasis added). This is an unusual statement, considering that the Directors of the National Nuclear Laboratories are responsible for managing the technical work that is required to certify to the President that U.S. nuclear weapons stockpile remains safe, secure, and effective annually, not once in 10 or however many years. Can D’Agostino foresee all changes in devices comprised of thousands of different parts that have to work with split-second precision? Unlikely, according to some experts—and himself.

In 2008, D’Agostino stated, “The metallurgical and chemical issues we face with our aging warheads continue to be a technical challenge for our best scientists and risk of catastrophic technical failure occurring as our warheads age cannot be ruled out absolutely.” A catastrophic technical failure would require either a new warhead or an extensive fix, neither of which can likely be validated without a nuclear weapons test.

U.S. nuclear weapons are some of the most sophisticated devices. In the past, U.S. scientists and engineers were often surprised at how systems performed during nuclear weapons tests. David H. Sharp of the Los Alamos National Laboratory wrote in 2008,

While any clear indications of potential performance issues that are revealed by non-destructive and destructive inspections, non-nuclear experiments or simulations should be taken seriously, one cannot be sure that warning signs will be apparent, even for very serious problems.

The debate whether the United States needs to test its nuclear weapons has recently been revived as the Obama Administration renewed its push to obtain the Senate’s advice and consent to an already rejected Comprehensive Test Ban Treaty. The Administration sees this treaty as yet another step on the road to “nuclear zero,” a world without nuclear weapons.

The United States is the only nuclear state without a substantial nuclear weapons modernization program. President Obama’s commitments to infrastructure modernization, made pursuant to the Senate’s resolution of ratification to the New Strategic Arms Reduction Treaty, have not even survived a year after the treaty entered into force. China and Russia are building up their forces. North Korea is reportedly preparing to conduct yet another nuclear explosion. As more than 30 countries all over the world rely on the U.S. nuclear umbrella, this is not the time to enter into a treaty banning the explosive testing of nuclear weapons on a permanent basis.