AP FACT CHECK: US Anti-Missile System in S. Korea Has Limits

Neat certainties are rare in the North Korean nuclear crisis, which for decades has simmered and occasionally boiled over, without resolution.

So it was jarring to see the absolute confidence with which America's top Pacific commander described the ability of a contentious U.S. missile defense system, scheduled to be up and running in days in South Korea, to shoot down North Korean missiles.

" If it flies, it will die," Adm. Harry Harris Jr. told U.S. lawmakers at a hearing Wednesday.

Like nearly everything associated with the world's last Cold War standoff, the truth is muddier.

To test the admiral's assertion, The Associated Press asked a handful of specialists to weigh in on one of the biggest points of friction in Northeast Asia.

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THAAD has limits, unknowns

Harris does have some data to back up his bold statement.

After an early redesign, the Terminal High-Altitude Area Defense system, or THAAD, was reportedly successfully tested 12 times, according to Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics.

A controlled test, however, is a much different matter than an actual war, where large numbers of missiles will be fired with little or no warning.

"Things that work well at home on the test range don't always go as smoothly when deployed," McDowell said.

A salvo of multiple North Korean short-range missiles, for instance, could overwhelm THAAD, said David Wright, co-director of the Union of Concerned Scientists' Global Security Program.

THAAD will also be deployed about 200 kilometers (125 miles) south of Seoul, whose greater metropolitan area, about an hour from the heavily armed border, is home to 25 million. "It cannot engage missiles fired at Seoul, so it offers no additional protection of the city,'' Wright said.

Some scientists are even blunter.

Harris' comments about THAAD's capabilities "are technically incorrect," said Theodore Postol, a professor at the Massachusetts Institute of Technology. "The THAAD interceptor is very easily defeated by either causing a missile to tumble end over end, or by intentionally fragmenting a rocket into pieces."

THAAD's capabilities as a defense system "can be expected to be very low, probably zero or close to that," Postol said.

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The political angle

Viewed one way, Harris' declaration of confidence makes perfect sense.

A senior military official briefing lawmakers beholden to American taxpayers must show complete confidence in the very expensive piece of hardware that's about to be deployed in a skittish U.S. ally living in direct range of North Korean missiles.

"Just imagine an Air Force general saying that his new jet fighters, designed for air superiority, will not stand a chance against the enemy fighters," said Markus Schiller, a missile specialist in Germany. " The same is true for a missile defense system - once deployed, the commanding officer has to say it will work."

The U.S. admiral may also have been looking to soothe South Korea.

THAAD is a big issue ahead of the May 9 presidential election, with the leading candidate, liberal Moon Jae-in, vowing to reconsider the deployment if he wins.

Some South Koreans wonder why the United States and the caretaker government that took over for recently removed President Park Geun-hye rushed key parts of THAAD into place before dawn this week, prompting violent clashes between local villagers and police.

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The China angle

Another subtext to the admiral's comments on THAAD is China.

Beijing says THAAD's powerful radar can be reconfigured to peer deep into its territory and monitor its flights and missile launches.

Seoul already sees moves by Beijing to retaliate, including limits on Chinese tour group visits to South Korea, which is increasingly dependent on Chinese tourism and demand for its industrial products.

Some experts are sympathetic with China's argument.

Postol said THAAD's radar can track Chinese intercontinental ballistic missiles flying below the curved earth horizon of U.S. missile defense radars in Alaska. It could then send and receive critical missile defense information to U.S. monitors.

"This makes it possible for the THAAD radar to quickly acquire ICBMs launched from China well before the ICBMs rise over the horizon where they could be then seen by U.S. national missile defense radars," Postol said.