• The US shot down a ballistic missile for the first time from Guam in a major test this week.
• The event comes as the Pentagon increasingly looks to protect key military infrastructure on Guam.
• Guam would almost certainly be a target in a war with China, which has missiles that can reach the island.

The US military shot down a ballistic missile for the first time from Guam this week, marking a significant step toward strengthening defenses on the Pacific island well within reach of China's long-range weapons.

The US Missile Defense Agency said on Tuesday that during the FEM-02 test, it "successfully conducted a live intercept of a ballistic missile target."

The test involved launching a top interceptor munition, the RIM-161 Standard Missile-3 Block IIA, jointly developed by RTX and Mitsubishi Heavy Industries, from the Aegis Guam System, an advanced air-defense battery. The SM-3, which costs nearly $30 million, then struck an air-dropped medium-range ballistic missile target off the coast from Guam's Andersen Air Force Base.

The Aegis Guam System, made by defense contractor Lockheed Martin, consists of an integrated AN/TPY-6 and vertical launch system based on the Mark 41 shipborne missile system. American warships, such as destroyers and cruisers, use these vertical launch systems to fire missiles and defend against incoming threats, as they have been doing for over a year in Middle East conflicts.

Lockheed said in a statement that the test gives the Department of Defense a better understanding of the Aegis Guam System's ability to counter missiles. It said the AGS could help "with pacing the Indo-Pacific threats." The Pentagon routinely characterizes China as its "pacing challenge."

Rear Adm. Greg Huffman, the commander of Joint Task Force-Micronesia, a senior command established earlier this year, hailed the missile test as "a critical milestone in the defense of Guam and the region."

The admiral said that "it confirmed our ability to detect, track, and engage a target missile in flight, increasing our readiness to defend against evolving adversary threats."

The newest test, the MDA said, is a step toward the future Guam Defense System; the agency explained that "the future is focused on defending Guam and protecting forces from any potential regional missile threats." As part of the US Pacific Deterrence Initiative, the US is planning to dramatically bolster Guam's defenses over the coming years.

Defending US forces from Chinese missiles

The intercept test comes as the Pentagon seeks ways to better protect important military infrastructure on Guam from China's expanding arsenal of ballistic missiles. DoD has repeatedly highlighted the Chinese missile threat in its annual China military power reports, yet there are concerns about readiness to confront the threat.

Some US lawmakers warned earlier this year that the US is unprepared for a potential Chinese missile strike on bases in the Indo-Pacific, highlighting the need for additional active and passive defenses.

The military installations on Guam routinely host American bombers and warships on rotational visits, as well as communications and surveillance operations, making the small island and its defense essential to US national security interests in the region. Chinese military planners also know the island's value.

China's People's Liberation Army Rocket Force boasts thousands of missiles, including the DF-26, a solid-fueled intermediate-range ballistic missile. The DF-26 is nicknamed the "Guam Express" because it can reach US forces on the island, some 2,500 miles from Beijing. It also has an anti-ship role, leading it to it sometimes being described as a "carrier killer." The Chinese military is also developing the DF-27 hypersonic missile expected to also be able to range Guam.

Chinese ballistic missiles have not been tested in combat, but conflict experts say that the US could face a threat unlike anything it's seen before in a conflict with Beijing. This potential scenario has underscored a need for more robust air defenses, and this effort is underway in Guam, which would be a key target.

"Within the context of homeland defense, a top priority for the Department of Defense, Guam is also a strategic location for sustaining and maintaining United States military presence, deterring adversaries, responding to crises, and maintaining a free and open Indo-Pacific region," the MDA said in a statement. There's long been a recognition that Guam needs more defenses. This test moves that forward.