Facts and figures

The ‘Know Your Region’ series is designed to support unit and individual professional military education on the Indo-Pacific region. It’s important for all serving members of our military to have a foundational knowledge of the countries and issues in the Indo-Pacific.

On this page:

  • A short history
  • Compact of Free Association (COFA)
  • Internal security
  • Security partners
  • Security challenges

A short military history

Germany purchased the Marshall Islands from Spain in 1885; however, they were seized by Japan with minimal resistance during WWI. With Germany’s defeat, administrative control was granted to Japan by the League of Nations as part of the South Seas Mandate. During the interwar years, Japan initially administered the islands through a civilian-military hybrid government with the primary focus being economic development, particularly copra production.

By the late 1930s, as a second global conflict looked more likely, Japan began a secret and rapid program of fortification. Kwajalein, Jaluit, and Mili were turned into ‘unsinkable aircraft carriers’, designed to protect the Japanese mainland and project power across the Central Pacific. Marshallese people were conscripted into forced labour to build airstrips and bunkers with little or no compensation.

By 1944, the Marshall Islands had become a critical part of the US "island-hopping" strategy. The Battle of Kwajalein (Operation Flintlock) and the Battle of Eniwetok (Operation Catchpole) were among the most intense amphibious assaults of the Pacific War.

The Pacific Strategy, 1941-1944 | The National WWII Museum | New Orleans

U.S. forces used massive naval and aerial bombardments to crush Japanese defences. After capturing Kwajalein, the U.S. immediately transformed it into a massive logistical and staging base for the subsequent invasions of the Marianas and eventually the Japanese home islands. The victory in the Marshalls effectively broke the outer perimeter of the Japanese Empire, shifting the momentum of the war decisively in favour of the Allies.

Following the war, the UN established the Trust Territory of the Pacific Islands (TTPI), with the US as the sole administering authority. Between 1946 and 1958, the Marshall Islands became the site of 67 US nuclear tests. The most significant was Operation Castle Bravo which was detonated on March 1, 1954. Although the blast was meant to be no greater than 5-6 megatons, the yield was closer to 15 megatons. With the winds shifting, inhabited islands were exposed to radioactive debris. Despite this disaster, nuclear tests increased before a temporary moratorium on testing came into effect signed by Russia, the US, and the UK.

In the 1960s, Kwajalein Atoll was developed into the Ronald Reagan Ballistic Missile Defence Test Site. Its massive lagoon serves as a "catcher's mitt" for Intercontinental Ballistic Missiles (ICBMs) launched from Vandenberg Space Force Base in California. This site remains one of the most critical assets in the U.S. global defence network, used for testing missile accuracy and anti-missile interceptors.

The Compact of Free Association (COFA)

In 1986, the Marshall Islands transitioned from a trust territory to a sovereign nation in Free Association with the US. Under the compact, the US has full authority and responsibility for the security and defence of the Islands. This includes the "right of strategic denial," allowing the US to prevent any third-party military (such as China) from accessing the islands' territory or waters. In exchange for these strategic rights, the US provides financial aid and allows Marshallese citizens to live and work in the U.S. indefinitely without visas.

Internal Security

Internal security is primarily handled by the Marshall Islands National Police, which has an estimated strength of a few hundred officers nationwide, concentrated mainly in urban centres such as Majuro and Ebeye. The Marshall Islands Police (Maritime Division) is responsible for law enforcement and safety at sea, while full offshore patrols are mainly handled by the separate Maritime Surveillance Division (MSD).

The MSD operates under the Ministry of Justice and works closely with the National Police, Customs, and regional partners to safeguard the nation’s vast Economic Exclusion Zone (EEZ). Additionally, the Marshall Islands utilise "Shiprider Agreements" with the US Coast Guard, which allow Marshallese law enforcement officers to board US vessels to patrol their own waters, effectively "borrowing" the muscle of the American military to protect their sovereignty.

Security Challenges

Geopolitics

The Marshall Islands are at the epicentre of a strategic tug-of-war between the US and China. While the US holds the right of strategic denial, China has increasingly used "soft power" security tactics, such as infrastructure investment and economic aid, to win favour. In response, the US has ramped up its diplomatic presence, recently renewing the COFA economic provisions through 2043 with a $2.3 billion package. This has guaranteed the continued operation of the Kwajalein Reagan Test Site, which is indispensable for tracking North Korean and Chinese missile launches.

Climate Change

Most of the Marshall Islands are only one to two metres above sea level, making them highly vulnerable to sea-level rise, coastal erosion, and storm surges. Increasing ocean temperatures and acidification are damaging coral reefs that protect shorelines and support fisheries, while saltwater intrusion is contaminating freshwater lenses beneath the atolls. This has already reduced the availability of safe drinking water and damaged traditional crops such as breadfruit and pandanus. What were once rare disasters have turned into regular disruptions to daily life.

Internal displacement is already occurring as people move from outer islands to overcrowded urban centres such as Majuro, placing strain on housing, health services, and infrastructure. In the long term, the possibility of cross-border migration has raised fears of loss of national identity.

The nation’s vast Exclusive Economic Zone (EEZ) is central to the economy, particularly through fishing licence revenue. If islands become uninhabitable or submerged, there is concern under international law that maritime zones could be challenged.

Climate change is also placing some islands at risk due to past nuclear testing, particularly Enewetak Atoll, where radioactive waste from US nuclear test sites is contained in the Runit Dome. Rising seas, coastal erosion, and cracking of the dome has increased the risk of radioactive material leakage into the surrounding soil and ocean.

To address climate change, the Marshallese government has created a "survival plan" that combines local action with international pressure. The ‘National Adaptation Plan’ (NAP) was developed under the UN climate framework and focuses on coastal protection, water security, food systems, health services, and infrastructure. It guides projects such as shoreline reinforcement, climate-resilient housing, rainwater harvesting, protection of freshwater lenses, and the safeguarding of fisheries and reefs. The plan also addresses climate-driven displacement, urban overcrowding, and disaster preparedness, while emphasising the need to protect maritime boundaries and the Exclusive Economic Zone even if land is lost.

Security Partnerships

United States

The United States is the Marshall Islands’ primary and legally responsible security partner under the COFA, first enacted in 1986 and renewed most recently in 2023-2024. Under COFA the US is responsible for the defence of the Marshall Islands, has exclusive military access to Marshallese territory, surrounding airspace and waters, and can deny third‑party military access. Other aspects include the Kwajalein Atoll missile testing and space surveillance facilities, US Indo‑Pacific Command activities and Joint Task Force–Micronesia, Maritime security cooperation (e.g. shiprider agreements to combat illegal fishing), and National Guard partnerships focused on maritime domain awareness and cyber security.

Australia 

Australia plays a complementary role in Marshallese security – particularly in maritime security, capacity building, and regional cooperation, rather than defence in the traditional military sense. Support includes the provision and sustainment of patrol vessels, training for crews, and technical assistance. Through initiatives such as the Pacific Maritime Security Program, Australia helps ensure the Marshall Islands can patrol its EEZ, deter illegal, unreported, and unregulated fishing, and maintain sovereignty over its ocean resources, which is critical to the economy.

Marshallese personnel receive training in maritime law enforcement, navigation, search and rescue, maintenance, and command and control systems. It is designed to build long-term self-reliance rather than short-term enforcement capability. Australia also plays an important role in humanitarian assistance and disaster response (HADR), which is increasingly becoming a major security threat.

Japan

Similar to Australia, Japan provides non-military cooperation that is focused on maritime safety, economic security, and human security. Through the Japan International Cooperation Agency (JICA), Japan has provided patrol boats, port equipment, navigation aids, and training to numerous Pacific Island states, including the Marshall Islands. This assistance helps improve law enforcement at sea, search and rescue capability, and safe navigation.

For more information on Marshall Island security, see the resources below:

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