By Phil Stewart and Idrees Ali

WASHINGTON (Reuters) – The United States said on Tuesday it shot down a simulated, incoming intermediate-range ballistic missile similar the ones being developed by countries like North Korea, in a new test of the nation’s defenses.

Planned months ago, the U.S. missile defense test over the Pacific Ocean has gained significance after North Korea’s July 4 launch of an intercontinental ballistic missile heightened concerns about the threat from Pyongyang.

The test was the first-ever of the Terminal High Altitude Area Defense system against an incoming IRBM, which experts say is a faster and more difficult target to hit than shorter-range missiles.

The U.S. Missile Defense Agency said the IRBM was designed to behave similarly to the kinds of missiles that could threaten the United States.

“The successful demonstration of THAAD against an IRBM-range missile threat bolsters the country’s defensive capability against developing missile threats in North Korea and other countries,” the Missile Defense Agency said in a statement.

The United States has deployed THAAD to Guam and South Korea to help guard against threats from North Korea. A ground-based missile defense system, THAAD is designed to shoot down short-, medium- and intermediate-range ballistic missiles.

In the latest test, a THAAD in Kodiak, Alaska, intercepted a ballistic missile target that was air-launched from a C-17 aircraft flying north of Hawaii, the Missile Defense Agency said in a statement.

This success leaves THAAD with a 100 percent track record for all 14 intercept attempts since flight testing began just over a decade ago.

Lockheed Martin Corp <LMT.N>, the prime contractor for the THAAD system, said it could intercept incoming missiles both inside and outside the Earth’s atmosphere.

The United States deployed THAAD to South Korea this year to guard against North Korea’s shorter-range missiles. That has drawn fierce criticism from China, which says the system’s powerful radar can probe deep into its territory.

Earlier this month Moscow and Beijing, in a joint statement, called on Washington to immediately halt deployment of THAAD in South Korea.

The statement said Washington was using North Korea as a pretext to expand its military infrastructure in Asia and risked upsetting the strategic balance of power in the region.

THAAD’s success rate in testing is far higher than the one for America’s Ground-based Midcourse Defense system, which is designed to shoot down an ICBM headed for the U.S. mainland.

That GMD system has only a 55 percent success rate over the life of the program. But advocates say the technology has improved dramatically in recent years.

The GMD system successfully shot down an incoming, simulated North Korean ICBM in a test in May.

That led the Pentagon to upgrade its assessment of the United States’ ability to defend against a small number of ICBMs, according to an internal memo seen by Reuters.

The Missile Defense Agency told Congress in June that it planned to deliver 52 more THAAD interceptors to U.S. Army between October 2017 and September 2018, bringing total deliveries to 210 since May 2011.

(Writing by Susan Heavey and Phil Stewart; Editing by Jeffrey Benkoe and Lisa Von Ahn)