U.S. missile defense system is effective but not foolproof against North Korea

WASHINGTON — If North Korea fires a missile toward Guam, as it has threatened, there is a good chance that the U.S. military or an ally will be able to shoot it down.

The United States and allies in the Pacific have an effective, though not foolproof, defense against a North Korea missile launch in the region, analysts say.

“We have an important but limited degree of protection,” said Thomas Karako, an analyst at the Center for Strategic and International Studies. “Nobody thinks that this is a perfect shield.”

Defense Secretary Jim Mattis said Monday that if a missile were on track to hit Guam "we will take it out." He also warned that if North Korea fires a missile at the United States, "it could escalate into war very quickly."

The Washington Post reported Monday that North Korea says leader Kim Jong Un was briefed on his military’s plans to launch missiles in waters near Guam days after the Korean People’s Army announced its preparing to create “enveloping fire” near the U.S. military hub in the Pacific.

Kim praised his military for drawing up a “close and careful” plan, the Post reported. Korean media said Kim will give the order for the missile test if the United States continues its “extremely dangerous actions” on the Korean Peninsula.

President Trump last week vowed "fire and fury like the world has never seen" if North Korea follows through on its threats and missile tests in defiance of international law.

The comments came amid growing tensions between Trump and Kim Jong Un's regime, which said it was preparing a plan to launch four missiles aimed off the coast of Guam, a U.S. territory and home to about 7,000 American military personnel.

The Trump administration later sought to lower the rhetoric, saying war is not imminent. Still, Marine Corps Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, warned during a visit to South Korea on Monday that the United States is ready to use the “full range” of its military capabilities to defend itself and its allies against North Korea.

The defenses include the ability to counter the Hwasong-12, an intermediate-range missile that can travel about 2,800 miles and was cited by North Korea in its threat to target Guam, which is about 2,100 miles away.

A missile of that range would be easier to intercept than a long-range intercontinental ballistic missile, which travels faster and spends much of its travel time outside the Earth's atmosphere.

Missile experts do not believe North Korea has developed decoy missiles designed to throw interceptors off the track, said Ian Williams, another analyst at the Center for Strategic and International Studies.

While U.S. missile defense systems have proven reliable in tests, they could be overwhelmed if an adversary launched multiple missiles at the same time.

Here are some of the key components of the U.S. missile defense system:

THAAD: The United States has deployed THAAD, or the Terminal High Altitude Area Defense, systems in South Korea and Guam. It is designed to intercept a warhead as it reenters the Earth’s atmosphere and is in the last stages of its flight. It is an accurate system that has passed all 15 tests it has undergone.

AEGIS: The aegis ballistic missile defense system is deployed on U.S. warships and is designed to intercept short- and intermediate-range missiles, such as the Hwasong-12. The ballistic defense systems are aboard 33 Navy ships, according to the Missile Defense Agency.

The system intercepts missiles “midcourse” — as the warhead is flying above the earth’s atmosphere. If the Aegis system misses, the THAAD could hit it after it reenters the atmosphere.

The aegis system has performed well in tests, said Michaela Dodge, an analyst at the Heritage Foundation.

PATRIOT : Patriot batteries are designed for short-range attacks and were used extensively during the 1990-91 Persian Gulf War against Iraq’s Scud missiles. More recently, they have performed well for Saudi Arabia and its allies by intercepting Iranian-supplied Scuds fired from Yemen in that country's civil war in Yemen.

It is the only missile defense system with extensive use in combat and is being used by 13 countries, according to the Center for Strategic and International Studies.

In response to the North Korea threat, Japan last week began moving Patriot units to Hiroshima, Kochi, Shimane and Ehime, according to the Associated Press. The moves are aimed at being able to intercept falling debris if North Korean missiles fly overhead.

GROUND-BASED DEFENSE SYSTEMS: These are interceptors designed to protect the U.S. mainland from missile threats, a threat that has grown more urgent since North Korea developed intercontinental ballistic missiles capable of reaching U.S. cities.

The U.S. military currently has 36 interceptors in silos in California and Alaska and another eight will be deployed by the end of this year to help defend against the threat from North Korea.

The interceptors have had mixed results in tests, though recent demonstrations have been successful in hitting their targets.

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