NEWS | I N D E P T H
1436
ARMS CONTROL
Not-seeing is believing “Zero knowledge” tests could let inspectors identify a nuclear weapon without learning the secrets of its design By Richard Stone
I
n nuclear arms control, the catchphrase “trust, but verify” gets you only so far. It’s simple to count nukes deployed on intercontinental ballistic missiles, heavy bombers, or submarines: Just tally up the delivery systems. But verifying the number and types of nuclear warheads in storage—as future accords will require—is another story. No nuclear power would permit verification tests that reveal secret warhead designs. Now, there may be a solution to this conundrum. Researchers have devised a way to verify a nuclear warhead’s identity without laying eyes on it. Known as a zeroknowledge protocol, a name adopted from a technique used in cryptography, their proposal is setting the arms control community abuzz. It’s an “ingenious solution,” says physicist James Acton, a nonproliferation
Nuclear armed Estimated number of warheads, 2014 Russia
8,000
United States
7,315
France
300
China
250
United Kingdom
225
Israel
80
Pakistan
100–120
India
90–110
North Korea
1436
ARMS CONTROL
Not-seeing is believing “Zero knowledge” tests could let inspectors identify a nuclear weapon without learning the secrets of its design By Richard Stone
I
n nuclear arms control, the catchphrase “trust, but verify” gets you only so far. It’s simple to count nukes deployed on intercontinental ballistic missiles, heavy bombers, or submarines: Just tally up the delivery systems. But verifying the number and types of nuclear warheads in storage—as future accords will require—is another story. No nuclear power would permit verification tests that reveal secret warhead designs. Now, there may be a solution to this conundrum. Researchers have devised a way to verify a nuclear warhead’s identity without laying eyes on it. Known as a zeroknowledge protocol, a name adopted from a technique used in cryptography, their proposal is setting the arms control community abuzz. It’s an “ingenious solution,” says physicist James Acton, a nonproliferation
Nuclear armed Estimated number of warheads, 2014 Russia
8,000
United States
7,315
France
300
China
250
United Kingdom
225
Israel
80
Pakistan
100–120
India
90–110
North Korea
