From a military perspective, this modernization has paid off: A U.S. nuclear first strike could quickly destroy China’s strategic nuclear arsenal. Whether launched in peacetime or during a crisis, a preemptive strike would likely leave China with no means of nuclear retaliation against American territory. And given the trends in both arsenals, China may live under the shadow of U.S. nuclear primacy for years to come.
This assessment is based on unclassified information, standard targeting principles, and formulas that defense analysts have used for decades. (And we systematically chose conservative estimates for key unknowns, meaning that our analysis understates U.S. counterforce capabilities.) The simplest version of an American preemptive strike would have nuclear-armed submarines in the Pacific launch Trident II missiles at the Chinese ICBM field in Henan province. The Navy keeps at least two of these submarines on “hard alert” in the Pacific at all times, meaning they’re ready to fire within 15 minutes of a launch order. Since each submarine carries 24 nuclear-tipped missiles with an average of six warheads per missile, commanders have almost 300 warheads ready for immediate use. This is more than enough to assign multiple warheads to each of the 18 Chinese silos. Chinese leaders would have little or no warning of the attack.
During the Cold War, U.S. submarines posed little danger to China’s silos, or to any other hardened targets. Each warhead on the Trident I missiles had little chance—roughly 12 percent—of success. Not only were those missiles inaccurate, their warheads had a relatively small yield. (Similarly, until the late 1980s, U.S. ICBMs lacked the accuracy to carry out a reliable disarming attack against China.) But the Navy’s new warheads and missiles are far more lethal. A Trident II missile is so accurate, and the newer W88 warhead so powerful, that if the warhead and missile function normally, the destruction of the silo is virtually assured (the likelihood is calculated as greater than 99 percent).
In reality, American planners could not assume such near-perfect results. Some missiles or warheads could malfunction: One missile’s rockets might fail to ignite; another’s guidance system might be defective. So a realistic counterforce plan might assign four warheads to each silo. The U.S. would “cross-target” the missiles, meaning that the warheads on each missile would each go to different silos, so that a silo would be spared only if many missiles malfunctioned. Even assuming that 20 percent of missiles malfunctioned—the standard, conservative assumption typically used by nuclear analysts—there is a 97 percent chance that every Chinese DF-5 silo would be destroyed in a 4-on-1 attack. (By comparison, a similar attack using Cold War–era Trident I missiles would have produced less than a 1 percent chance of success. The leap in American counterforce capabilities since the end of the Cold War is staggering.)
Beyond bolstering the ability to conduct a first strike, the improvements to U.S. counterforce weapons also allow war planners to design nuclear options that will make the weapons more “usable” during high-stakes crises. Nuclear planners face many choices when they consider striking a given target. First, they must choose a warhead yield. The American arsenal includes low-yield weapons such as the B-61 bomb, which can detonate with as little explosive force as 0.3 kilotons (one-fiftieth the power of the bomb that destroyed Hiroshima), and high-yield weapons such as the B-83 bomb, which can yield 1,200 kilotons (80 times the strength of the Hiroshima bomb). For a military planner, high-yield weapons are attractive because they’re very likely to destroy the target—even if the weapon misses by some distance. Low-yield warheads, on the other hand, can be more discriminating, if planners want to minimize civilian casualties.
A second key decision for war planners is whether to set the weapon to detonate at ground level or in the air above the target. A groundburst creates enormous overpressure and ground shock, ideal for destroying a hardened target. But groundbursts also create a lot of radioactive fallout. Dirt and other matter is sucked up into the mushroom cloud, mixes with radioactive material, and, after being carried by the wind, falls to earth in the hours after the blast, spreading lethal radiation.
Airbursts create smaller zones of extremely high overpressure, but they also generate very little fallout. If the detonation occurs above a threshold altitude (which depends on the weapon yield), virtually no heavy particles from the ground mix with the radioactive material in the fireball. The radioactive material rises into the high atmosphere and then falls to earth over the course of several weeks in a far less dangerous state and over a very wide area, greatly reducing the harm to civilians.
In the past, a nuclear attack on China’s arsenal would have had horrific humanitarian consequences. The weapons were less accurate, so an effective strike would have required multiple high-yield warheads, detonating on the ground, against each target. The Federation of American Scientists and the Natural Resources Defense Council modeled the consequences of such an attack—similar to the submarine attack described above—and published their findings in 2006. The results were sobering. Although China’s long-range missiles are deployed in a lightly populated region, lethal fallout from an attack would travel hundreds of miles and kill more than 3 million Chinese civilians. American leaders might have contemplated such a strike, but only in the most dire circumstances.
But things are changing radically. Improved accuracy now allows war planners to target hardened sites with low-yield warheads and even airbursts. And the United States is pushing its breakthroughs in accuracy even further. For example, for many years America has used global-positioning systems in conjunction with onboard inertial-guidance systems to improve the accuracy of its conventionally armed (that is, nonnuclear) cruise missiles. Although an adversary may jam the GPS signal near likely targets, the cruise missiles use GPS along their flight route and then—if they lose the signal—use their backup inertial-guidance system for the final few kilometers. This approach has dramatically improved a cruise missile’s accuracy and could be applied to nuclear-armed cruise missiles as well. The United States is deploying jam- resistant GPS receivers on other weapons, experimenting with GPS on its nuclear-armed ballistic missiles, and planning to deploy a new generation of GPS satellites—with higher-powered signals to complicate jamming.
The payoff for equipping cruise missiles (or nuclear bombs) with GPS is clear when one estimates the civilian casualties from a lower-yield, airburst attack. We asked Matthew McKinzie, a scientific consultant to the Natural Resources Defense Council and coauthor of the 2006 study, to rerun the analysis using low-yield detonations compatible with nuclear weapons currently in the U.S. arsenal. Using three warheads per target to increase the odds of destroying every silo, the model predicts fewer than 1,000 Chinese casualties from fallout. In some low-yield scenarios, fewer than 100 Chinese would be killed or injured from fallout. The model is better suited to predicting fallout casualties than to forecasting deaths from the blast and fire, but given the low population in the rural region where the silos are, Chinese fatalities would be fewer than 6,000 in even the most destructive scenario we modeled. And in the future, there may be reliable nonnuclear options for destroying Chinese silos. Freed from the burden of killing millions, a U.S. president staring at the threat of a Chinese nuclear attack on U.S. forces, allies, or territory might be more inclined to choose preemptive action.