January 1, 2017–We are moving to a new presidency. Our new president promises a widescale construction program in new nuclear weapons, reversing the trend of reducing dependence on these dangerous instrumentalities that has been underway since Ronald Reagan’s time. In part Donald J. Trump seems to regard this as an answer to Russian leader Vladimir Putin’s similar promises to build new nukes to counter the system of U.S. missile detection radars and defense mechanisms going into place in Eastern Europe. In part a nuclear buildup will form part of a larger, poorly conceived, Trump administration Pentagon budget that will simply increase spending in every category rather than imposing fiscal discipline on programs that have long run without it.

Our outpourings of grief for people lost in the past year have been heavily tilted toward musicians, actors and cultural personalities. Two of the names missing on those lists could have been vastly helpful in the period we are about to enter. They passed away within a week of each other in December 2016–not quite as close as Carrie Fisher and her mom, Debbie Reynolds, but awfully evocative. One was Harvard economist Thomas C. Schelling, the other Sidney D. Drell, the theoretical physicist who trained at the University of Illinois. Schelling made seminal contributions to game theory, including the escalation dominance and hedging mechanisms that lie at the heart of nuclear strategy. With Bernard Brodie and Herman Kahn, Schelling can indeed be viewed as a father of this school–and in fact he was a plankholder in the creation of Harvard’s Kennedy School. Drell became a founder also–of the JASON Group of scientific experts who counseled the Pentagon on all manner of issues. Drell’s contributions to particle physics were considerable and he remained associated until his death with the Stanford Linear Accelerator. But for our purposes today it is Drell’s forthright advocacy–over decades–of nuclear arms reductions that is important. He sought earnestly for a world without nuclear weapons. Both provide insights to us today.

First, what is Trump talking about as a nuclear buildup? Only certain things are possible. The most obvious is expansion of the ballistic missile defenses currently being installed in Alaska and Eastern Europe. These are represented as oriented toward stopping potential North Korean or Iranian missile attacks. But these deployments are precisely the ones that have aggravated Putin–and accounted for a good measure of the decline in Russian-American relations that began during George W. Bush’s presidency and until now has not been reversed. As president, especially one who esteems Putin as he claims to do, Mr. Trump would be unlikely to focus his buildup here.

What other possibilities are there? As a matter of fact there are no new-generation U.S. ballistic missiles, bombers, or other weapons carriers under design or in production. Efforts for over a decade have actually centered on creating more powerful conventional explosives to de-nuclearize ICBMs and SLBMs. New nuclear weapons designs have been projected, and may have been modeled using the more sophisticated simulations that have become our substitute for actual weapons tests. These are the only nuclear force elements with anything like near-term prospects, though building next-generation warheads is often spoken of as a multi-decade initiative. If so, a buildup based on these elements is likely to incur Russian anger today, while not offering any practical result for a long interval past Donald Trump’s presidency. The engineering development of new nuclear weapons would increase demands for real, physical nuclear tests, and that, too, would spark Russian hostility. Sidney Drell would surely label that course absurd.

The last time the U.S. was embarked on nuclear deployments we were on the verge of producing new-generation guidance systems when arms reduction agreements and the end of the Cold War changed the dynamics of international relations. A resurrection of accuracy-enhancing programs (such as the Maneuverable re-entry vehicle, or MARV)would be a likely avenue for the new arms race. The destructive power of nuclear weapons depends on a combination of accuracy and yield–and of the two accuracy is the more probable near-term development. However, Mr. Putin, in threatening to counter U.S. missile defenses, has to be aware that maneuverable re-entry vehicles (though expensive) offer greater benefits than other types of penetration aids. Igniting an arms competition for MARVs is not in U.S. interest. Tom Schelling would mark it down as a stupid, tragic, strategy, in particular because it would trend toward unraveling many of the confidence-building measures of past decades (emptying the pre-stored target parameters of guidance systems; taking missiles off alert status, etc).

A nuclear arms buildup will not improve United States security. To speak of engaging in an arms race “until” other countries “understand” nuclear weapons, as Mr. Trump has done, is the height of folly.