U.S. Strategic Force Posture for the Third Nuclear Age

A Response by Matthew Kroenig

Several recent secretaries of defense have stated that nuclear deterrence is the #1 priority of the U.S. Department of Defense. Unfortunately, as Tim Morrison brilliantly explains in his essay, the nation has allowed its nuclear forces and underlying infrastructure to decay to dangerous levels of disrepair. Aging nuclear forces have been extended well past their intended service life, modernization programs have been pushed off too far into the future, and there is a real risk of a capability gap in the late 2020s and early 2030s. Old systems may need to be retired before new systems are ready, and the United States may not be able to field enough nuclear forces to meet its deterrent requirements. This is a disgrace. Fully funding and modernizing America’s strategic forces should be among Washington’s highest priorities. We can afford national survival. Some suggest a tradeoff between defense spending on nuclear and conventional weapons, but the United States must fully fund both.

Rather than repeat the themes of Morrison’s trenchant essay, I will attempt to complement it, by describing the strategic environment, American nuclear strategy, and the posture that America’s nuclear modernization programs will need to support.

The United States is entering a third nuclear age. The first nuclear age was the First Cold War. Nuclear weapons were central to U.S. defense strategy, and America and its principal rival, the Soviet Union, engaged in a decades-long strategic arms competition. The second nuclear age was the post-Cold War period from 1989 to 2022. In this period, nuclear weapons did not feature prominently. Nuclear reductions and arms control were relatively easy. Those days are over. The third nuclear age is the new Cold War we are now entering. American nuclear strategy and posture will need to adjust and adopt a Cold War footing fit for 21st-century realities. 

The United States is entering the most dangerous nuclear threat environment in its history. China is engaging in an unprecedented strategic force buildup, and the Department of Defense estimates that China will possess 1500 nuclear weapons by 2035. This means that, for the first time ever, the United States will need to deter two peer nuclear rivals, Russia and China, at the same time. In addition, there is North Korea, which is the third U.S. rival with the ability to hold the homeland at risk with the threat of nuclear war. Finally, it is possible that Iran will be a nuclear-armed state by the end of the Biden administration. How can the United States deal with these threats?

The basics of American nuclear strategy are sound and do not need to be updated. The United States should continue to use nuclear weapons to deter strategic nuclear and nonnuclear attacks against itself and its allies. Washington should continue to assure allies. And it should continue to be prepared to achieve our objectives if deterrence fails. This will require the ability to assure retaliation against U.S. adversaries even after absorbing a first strike. It will require holding at risk that which the adversary values, which in the case of our autocratic rivals means: military forces (including nuclear forces), leadership, and war-supporting industry. The United States should not move to a “countervalue” targeting policy or a “minimum deterrent.” It will also require a force that provides the president with a range of “flexible response” options.

While U.S. nuclear strategy does not need to change, U.S. force posture to support that strategy will need to adapt to the realities of a two-peer environment. Unfortunately, Washington does not get to choose how our enemies sequence their aggression, and planning for only one war at a time is planning to fail. The United States must be able to deter China and Russia simultaneously. The United States can no longer size a nuclear force for parity with Russia and assume that this is also sufficient for China. Instead, the United States needs to size a force to hold at risk necessary targets in both China and Russia.    

This means that, for the first time since the end of the First Cold War, the United States will need to increase the size of its strategic deployed force. The current force of 1,550 nuclear weapons was designed in 2010 during a much more benign security environment. As China’s nuclear forces grow, the number of targets the United States must hold at risk, and, therefore, the number of nuclear weapons Washington requires, is increasing. This does not mean that the United States needs as many nuclear weapons as Russia and China combined. But, to hold the necessary targets at risk, it will need to increase beyond 1,550 deployed warheads. In the short-term, this can be done by uploading warheads onto ICBMs and SLBMs (although this will not be simple, as Morrison points out). Over the longer-term, the United States should plan to purchase larger numbers of new B21 bombers, LRSO missiles, and Colombia-class submarines.

This also means that the next Republican president will need to withdraw from the New START arms control treaty if it is still in place.

Next, the United States must strengthen its theater nuclear forces. During the First Cold War, the United States deployed theater nuclear forces in Europe and Asia to convince both adversaries and allies that America’s nuclear umbrella hung over any regional conflict and to buttress our conventional forces. During the second nuclear age, the United States almost completely disarmed itself of this category of weapons. Washington now faces a significant disadvantage in theater nuclear forces. China possesses hundreds, if not thousands, of short-, medium-, and intermediate-range missiles that can be armed with nuclear or conventional warheads. Russia possesses thousands of theater nuclear weapons from torpedoes to short-range, ground-launched missiles. The United States has zero nuclear weapons deployed in Asia and roughly two hundred, mostly useless, gravity bombs in Europe. 

The United States needs to rectify this deficit. It does not need to match Russia and China warhead for warhead and system for system, but it does need to develop and deploy nonstrategic nuclear weapons in Europe and Asia that are: survivable, mobile, low-yield, and capable of penetrating enemy defenses. Specifically, the United States should develop SLCM-N in the short term. It should also consider a mobile, ground-launched cruise missile, and nuclear-armed, theater-based, hypersonic missiles. 

Finally, Washington should shift its homeland missile defense policy to address threats from China and Russia. In the past, Washington maintained that homeland missile defenses were designed to defend against threats from rogue states only, like Iran and North Korea. But the Chinese and Russian missile threats to the U.S. homeland are growing, and these adversaries are building air and missile defenses against us. The United States cannot build an impenetrable shield against large-scale Russian or Chinese attack. But it can build a limited missile defense system designed to stop a small-scale missile attack from any adversary, including China and Russia. Washington should shift its policy in this direction and invest in next-generation missile defense technologies, including space-based sensors and interceptors. 

America does not want a new Cold War, but Beijing and Moscow are forcing it upon us. We need a strengthened strategic posture to secure American interests in this third nuclear age.