The Missile Defense Agency and Navy for the first time shot down two simulated ballistic missile targets yesterday off Kaua'i as the U.S. military heads toward a 2009 goal for operational use.

The latest "hit to kill" intercept test marked the 10th and 11th successful intercepts, out of 13 targets, for the Aegis Ballistic Missile Defense program, the sea-based component of the nation's still-developing missile defense program, officials said.

The shoot-down was conducted by the Pearl Harbor-based cruiser USS Lake Erie. At 6:12 p.m., a target missile was launched from the Pacific Missile Range Facility at Barking Sands. Moments later, a second identical target was launched.

The Lake Erie's Aegis weapons system detected and tracked the targets. About two minutes later, Lake Erie's crew fired two SM-3 missiles, and two minutes after that, they successfully intercepted the targets outside the Earth's atmosphere more than 100 miles above the Pacific Ocean and 250 miles northwest of Kaua'i.

A Japanese destroyer, the JS Kongo, also participated in the flight test as a training exercise in preparation for the first ballistic missile live-fire intercept test by a Japanese ship, scheduled for December.

"This is a historic event, obviously, with the simultaneous engagement, but also having our first international partner and our strongest contributor to sea-based missile defense, Japan, (testing its ballistic missile shoot-down capability) next month, is pretty exciting stuff," said Rear Adm. Brad Hicks, the Missile Defense Agency's Aegis ballistic missile defense program director.

The Aegis system guided the SM-3 intercept missiles through its first, second and third stages. Each SM-3 carries a kinetic warhead that ejects from the third stage and crashes into the target missile. Yesterday's test was delayed by several hours when boaters strayed into the Pacific Missile Range Facility.

Hicks said the successive intercepts tested a broader range of the Lake Erie's SPY-1B radar, which also have to monitor for other threats.

"Radar resources are finite, so it stresses the weapons system," Hicks said. Aegis ships with the SM-3 missiles are designed to be able to shoot down multiple ballistic missiles.

The Aegis ship-based capability is designed to intercept short- to intermediate-range ballistic missile threats. For example, Hicks said, a ship in the Sea of Japan could defend the island nation from a missile attack.

The Missile Defense Agency and Navy are modifying 15 destroyers and three cruisers to have Aegis ballistic missile defense capabilities.

Sixteen of the 18 Aegis ships with missile shoot-down capability will be based in the Pacific. At least four will be based at Pearl Harbor, including the cruisers Lake Erie and Port Royal, and destroyers Russell and Hopper.

The Japanese are adapting four destroyers for ballistic missile defense.

Reach William Cole at wcole@honoluluadvertiser.com.