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Why Guam’s Missile Defense Modernization Matters

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Why Guam’s Missile Defense Modernization Matters

Guam is a vital node of U.S. power projection in the Indo-Pacific. It’s also a key target for enemy strikes.

Why Guam’s Missile Defense Modernization Matters

A Terminal High Altitude Area Defense, or (THAAD) weapon system assigned to Task Force Talon, 94th Army Air and Missile Defense Command. Andersen Air Force Base, Guam, Oct. 26, 2017.

Credit: Photo by Army Capt. Adan Cazarez

Hosting two of the U.S. military’s most crucial facilities in the Pacific, Andersen Air Force Base and Guam Naval Base, the island of Guam has emerged as both an indispensable facilitator of the United States’ ability to project military force into East Asia and as a leading potential target for regional adversaries should war break out. Although considered near unassailable during the Cold War by any party other than the Soviet Union, advances in Chinese and North Korean capabilities have since left the territory increasingly vulnerable, leading the U.S. military to invest in developing alternative facilities. Notable examples include Wake Island, where major airfield expansion began in 2020, and northern Australia, where bases have hosted a growing marine presence and long-range bombers. The parallel emergence of a focus on “austere airfield” exercises on Guam itself may also allow U.S. Air Force assets to better retain some operational capacity if facilities are struck. 

The North Korean Hwasong-12 and Chinese DF-26 ballistic missiles have both been dubbed “Guam Killer” weapons, with the former entering service in 2017 and most recently seeing its capabilities demonstrated during a test flight in January. North Korea’s new hypersonic glide vehicles, unveiled and tested from September 2021, have made the threat to U.S. facilities, possibly including those as far away as Guam, significantly greater. North Korean forces’ ability to strike Guam dates back to the 2000s with early variants of the Hwasong-10 ballistic missile, better known as the Musudan, but has since expanded considerably, including fielding of a growing submarine based ballistic missile strike capability.

Chinese capabilities are significantly greater still, and include the ability to launch a wide range of cruise and ballistic missiles and even gravity bombs from a fleet of over 250 H-6 bombers, some of which have flown near the island in shows of force during previous periods of high tensions. The H-6 was first seen carrying a hypersonic missile in 2020, and is speculated to also serve as a launch platform for the WZ-8 hypersonic drone. China’s growing fleet of tanker aircraft built around the new Y-20U jet has also raised the possibility that a wider range of air assets could operate as far as Guam in the event of a major war, while the country’s high endurance destroyers have begun to integrate hypersonic ballistic missiles of their own.

Although the ability to reliably defend against hypersonic glide vehicles is not expected to materialize for years to come, near-term advances in air defense capabilities can potentially improve Guam’s security against more conventional missile attacks using assets that make up the large majority of the Chinese and North Korean arsenals.

During an interview in the second week of August, head of the U.S. Missile Defense Agency Vice Admiral Jon Hill revealed that the agency, Army, and Navy were cooperating in the field with at least some improvements expected to be in place before 2026. The admiral highlighted that under the Biden administration’s budget for fiscal year 2023, funds were allocated for missile defense, including developing a defense capability against hypersonic missiles, and that there was “crossover in what they do” with the Army’s cruise missile defense, allowing the services’ efforts to complement one another. Under the plans, radars would provide “persistent 360-degree coverage… because of the evolved threat,” although the number and combination of interceptors, sensors, command and control nodes, and other components have not been finalized.

Guam’s current air defenses are built around the Terminal High Altitude Area Defense (THAAD) long-range anti-missile system first deployed to the island under the Obama administration, with a ground-based variant of the Navy’s Aegis system the Aegis Ashore, having been considered but rejected. The system would have provided Guam’s missile defenses with two of the most capable Western surface-to-air missiles ever designed, the SM-3 and SM-6, although the ground-based Aegis variant also faced rejection from Japan in 2020 after an initial interest was shown.

To complement longer ranged anti-ballistic missile systems such as THAAD or Aegis, the Israeli Iron Dome system has been tested on Guam. Although initially designed primarily for defense against rocket artillery, most famously those of Islamist militant groups in Gaza, the Dome can reportedly be used for cruise missile defense. While plans for large-scale Iron Dome acquisitions were canceled by the U.S. Army in 2021, shortly following performance failures in Israel itself, the Army’s Enduring Shield system currently under development is expected to provide a more capable alternative using ground-launched derivatives of the AIM-9X infrared guided air-to-air missile.

Even if all planned acquisitions are seen through, however, defenses deployed on land may well still represent only a fraction of the overall surface-to-air missile arsenals defending Guam – the bulk of which will likely be deployed from the Navy’s Aegis-equipped destroyers and cruisers operating nearby. 

The importance of Guam became well-publicized during escalations in North Korea-U.S. tensions in 2017, when Pyongyang threatened to carry out strikes on American bases on the island. Meanwhile the U.S. Air Force increased munitions supplies and bomber deployments on Guam considerably for use in the event of a potential war. According to then-Defense Secretary James Mattis, the Trump administration was at the time considering launching large-scale nuclear strikes on its East Asian adversary which he predicted would “incinerate a couple of million people” in North Korea. With Pyongyang and Washington remaining technically at war, Guam is expected to continue to be a key focal point for a potential military clash due to its importance to the United States’ ability to wage war across an ocean on the Korean Peninsula and strike targets in the region.

Previously in 2013, in response to progress in the Hwasong-10 missile’s development, the Obama administration deployed THAAD systems to Guam as a precaution against North Korean strikes. After launching a cyber warfare campaign, which may have slowed but failed to stop refinement of Pyongyang’s first “Guam Killer” missile, the Obama administration in 2016 seriously considered launching an attack on the country. Had this been initiated, stronger defenses on Guam would have been vital to blunting North Korean retaliatory strikes, with the country at the time still unable to strike strategic targets on the U.S. mainland (which it only demonstrated the capability for in 2017).

Much as Okinawa was indispensable to the United States’ ability to fight the Vietnam War, and the Japanese mainland to supporting the U.S.-led war effort in Korea from 1950-53, so too is the ability of facilities on Guam to function potentially decisive as to whether or not the United States can wage war successfully in the Western Pacific today – whether on the Korean Peninsula, in the Taiwan Strait, or in the South or East China Seas. In 1965, Commander of U.S. Pacific Forces Admiral Ulysses S. Grant Sharp had emphasized that “without Okinawa, we couldn’t continue fighting the Vietnam war.” This applies similarly if not more so to Guam for possible U.S. wars in the 21st century.

While the U.S. military is expected to continue its parallel pursuit of both strengthening Guam’s missile defenses and dispersing assets more widely to reduce the extreme reliance on the island, so too are China and North Korea set to continue rapidly enhancing their assets to strike it. With both East Asian states having lacked this capability during the Korean War, when even U.S. bases in Japan were far beyond their retaliation range, the ability to strike U.S. bomber bases and key logistics hubs are particularly prized today.