The Nuclear Option
Slowing a New
Arms Race Means Compromising on Missile Defenses
February 22, 2021
An intercontinental ballistic missile launch, Vandenberg Air Force
Base, California, August 2017
Ian Dudley / Reuters
Just days before it was due to expire, the
United States and Russia extended the New START treaty—the only major arms
control agreement left between the two powers. Its expiration would have marked
the first time since 1972 that the nuclear arsenals of Washington and Moscow
were not subject to some form of agreed limitations. The five-year extension,
however, is a one-time event. U.S. President Joe Biden now faces the question
of what should come next.
The welcome extension of New START comes
at a worrying moment. Although the United States and Russia have nowhere near
the number of nuclear weapons they possessed at the height of the Cold War,
both countries are again in the midst of an arms race. Over the past decade,
each side has developed new missiles, bombers, submarines, and capabilities to
shoot down satellites. Other countries, including China and even North Korea,
are warming up, too.
This renewed competition traces its
origins to 2001. In the wake of the September 11 terrorist attacks, U.S.
President George W. Bush announced that Washington would withdraw from the 1972
treaty limiting missile defenses, a step he argued was necessary to defend the
United States against a rogue nuclear strike. In the years that followed,
Russia and China responded with campaigns to modernize their nuclear arsenals,
fearing that new American capabilities would leave them vulnerable in ways that
Washington could exploit.
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If Biden wants to slow this arms race, he
will need to accept limits on the U.S. missile defense systems that drive it.
Such restrictions will be politically hard to swallow, but they are not without
precedent. When the United States first began working with Moscow to end the
Cold War arms race, both sides agreed to start by limiting missile defenses. If
Biden is to address the contemporary escalation underway today, he will need to
do the same.
DETERRENCE AND
DEFENSES
An implicit assumption in early thinking
about nuclear deterrence was that only a nuclear weapon could threaten another
nuclear weapon. It took more than one warhead to reliably destroy a missile in
a silo, so if both sides had about the same number of weapons, neither had
enough to disarm the other in a surprise first strike. Numerical parity—no
matter the actual number of weapons—was, almost by definition, stable.
In the late 1960s, however, that
assumption came under technological assault. The United States and the Soviet
Union began deploying new weapons that complicated the old models of
deterrence. The single most destabilizing development was the antiballistic
missile (ABM) system.
An instrument for shooting down attacking
missiles might sound like an entirely defensive capability. Both sides quickly
realized, however, that ABM systems profoundly altered the nuclear calculus.
Under conditions of parity, if an aggressor were to strike an adversary and
knock out its nuclear missiles, some of those weapons would inevitably survive,
allowing the recipient to return the favor. But what if the aggressor had an
ABM system? Then, when the victim struck back with the remains of its arsenal,
the ABM system could “mop up” any missiles the initial attack had missed. Under
these conditions, a first strike might make strategic sense.
If Biden wants to slow this arms race, he
will need to accept limits on U.S. missile defense systems.
The two superpowers tried to neutralize
this problem by acquiring new defenses that drove an already costly arms race
to new heights. Declassified documents show that, for a time, the United States
allocated more than 100 Minuteman ground-based missiles—about a tenth of its
force at the time—plus an unknown number of Polaris submarine-launched
missiles, solely to destroying a pair of modest Soviet defensive sites near
Moscow and Tallinn, Estonia.
Eventually, however, the Johnson
administration surmised that the Soviets would make a similar calculation and
send the conflict spiraling out of control. Limiting defenses would therefore
be an essential first step to constraining the nuclear arms race. Ultimately,
Washington was able to persuade the Soviets of the wisdom of this approach, and
in 1972, Soviet leader Leonid Brezhnev and U.S. President Richard Nixon signed
the ABM Treaty. The agreement limited each country to two missile defense sites
(later reduced to one each) with 100 interceptors apiece. Moscow and
Washington no longer had to stay ahead of each other’s defenses, so both were
eventually able to reduce their offensive nuclear forces.
THE ARMS RACE
REVIVES
After the Cold War, the United States
judged that “rogue states” could still threaten it with ballistic missiles, so
it continued to develop modest systems designed to counter them. Republicans
and Democrats spent the 1990s sparring over the need to pursue such defenses,
while Russia and China watched warily. Finally, in 2002, Bush pulled out
of the ABM Treaty, declaring that the United States needed new systems to address
emerging threats from states such as North Korea. So began a new phase in a
global arms race.
Russia responded to Washington’s gambit by
dusting off projects designed in the mid-1980s to defeat the Reagan
administration’s never realized “Star Wars” program. These included doomsday
torpedoes, nuclear-powered cruise missiles, hypersonic gliders, superheavy
intercontinental ballistic missiles (ICBMs), and antisatellite weapons. Russian
President Vladimir Putin unveiled many of these programs in March 2018 with an
explicit nod to U.S. missile defense policy. “During all these years since the
unilateral U.S. withdrawal from the ABM Treaty,” he told Russian lawmakers, “we
have been working intensively on advanced equipment and arms.” China, too, has
modified its nuclear forces in profound ways. Over the past two decades,
Beijing has developed a new generation of ICBMs, placed multiple warheads
on existing missiles, tested a hypersonic glider to deliver strategic weapons,
and demonstrated an antisatellite system. Both countries, of course, are
investing in their own defenses.
U.S. officials initially expressed
surprise at these developments—especially Russia’s outlandish new weapons—but
the purpose of such tools is no mystery. They are designed to evade and defeat
U.S. missile defenses: more warheads can overwhelm defensive systems;
antisatellite weapons could destroy the orbiters on which defenses depend; more
powerful missiles can fly over the South Pole, where the defenses can’t
intercept them. Neither Beijing nor Moscow is likely to restrict its new
weapons unless Washington places corresponding limits on the defenses that such
weapons were meant to defeat. If the Biden administration is serious about
reviving arms control agreements with Russia and bringing China into the fold,
it will need to compromise.
LIMITING DEFENSES
Successfully limiting defenses will be far
more complicated than merely reviving the 1972 ABM Treaty. Even when that
treaty’s limits were in place, the United States and other countries continued
developing systems for countering short-range missiles. By the 1990s, it was
clear that these so-called theater defenses, particularly in quantity, were
sophisticated enough to undermine the purpose of the ABM Treaty. That trend
continues today. In mid-November 2020, for instance, the U.S. Department of
Defense for the first time tested a sea-based theater defense system, the SM-3
interceptor, against an ICBM-class target. Although the test was highly
scripted, it largely erases any useful demarcation between strategic defenses
targeting long-range ballistic missiles and those designed to protect against
short-range missiles armed with conventional warheads.
The loss of an effective divide between
different defensive systems means the Biden administration can’t merely revive
the ABM Treaty and call it a day. Instead, it will have to adapt the treaty’s
general approach. The parties could, for example, limit themselves to a single
national or “homeland” defense system with a cap on the number of land-based
interceptors and radars, much as they did under the ABM Treaty. Doing so
would freeze the new defensive arms race at a manageable level: the United
States currently plans to deploy 64 ground-based interceptors at its primary
site in Alaska, with another four in California. Moscow’s ABM system also has
about 68 interceptors. Deployments of this size are too small to threaten
either Russia’s or the United States’ nuclear deterrents.
The existence of nuclear weapons entails
the risk of nuclear danger.
Alternatively, the United States could
agree to freeze its defenses at current levels in exchange for a commitment
from Russia and China to verifiably suspend testing and deploying new nuclear
capabilities designed to defeat U.S. defensive systems. It seems unlikely that
Moscow and Beijing will agree to abandon all such programs, but slowing the
arms race by eliminating some and limiting others would still be worth doing.
Theater defenses present a more difficult
problem. Systems such as the U.S. SM-3 or Russian S-400 are widely available,
are often deployed with regular military units, and are, at least in principle,
able to intercept some ICBMs. It is extremely hard to imagine any verifiable
way to limit the number of such systems. Biden’s team will have to find other
approaches to help minimize the threat these defenses pose to strategic
stability. Limiting testing against ICBM-class targets or restricting the areas
in which countries can deploy theater defenses might manage the threat,
especially if such a policy is accompanied by transparency and
confidence-building measures.
FACING
VULNERABILITY
Limiting missile defense systems will be
unpopular in the United States, especially among Republicans in
Congress. The argument against such restrictions has always been that to
accept them is to acquiesce to vulnerability. Without defenses, there is no
prospect of victory in a nuclear exchange and no U.S. military superiority—only
a common mortal danger shared with Russia, China, and even North Korea.
But the simple fact is that the existence
of nuclear weapons entails the risk of nuclear danger. Deterrence does not
function without the fear of catastrophe, and no country gets to opt out, not
even the United States. The Biden administration would do well to level with
the American public about what it means to base U.S. security on nuclear
deterrence. An arms control agreement limiting missile defenses would most
likely need to be a formal treaty, subject to review by the Senate. The Biden
administration would therefore need to expend considerable political capital
negotiating such an agreement and getting it through the Senate. Even then, a
future president could demolish that work—just as partisans have sought to
repeal the Affordable Care Act and torpedo the Iran nuclear deal.
In the end, a successful nuclear policy,
like climate change or mass shootings, may be simply too difficult for the U.S.
political system to handle. The country’s institutions may be too broken and
its politics too poisonous. But addressing the Cold War arms race felt
impossible, too. After the Berlin and Cuban nuclear crises, few observers would
have imagined that generals, senators, and presidents would ever come to see
defenses as dangerous and work with the Soviets, of all people, to change tack.
For a time, such arguments did indeed fall on deaf ears, as both sides built
ever-larger nuclear arsenals. Eventually, however, both governments came to see
that building tens of thousands of nuclear weapons was an unsustainable means
of deterrence, and a different approach became possible. To get there, leaders
had to be wise enough to see the opportunity—and brave enough to seize it.
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