The United States cannot deter a Chinese attack on Taiwan nor win a long war without Indonesia. In conjunction with Australia, Indonesia could ensure a virtually impassable maritime blockade of Chinese commerce, enforced with only land-based aircraft and light patrol ships and backed up by the U.S. Navy’s littoral combat ships. Its collaboration would also be crucial for the protection of all convoys proceeding to friendly Asian littoral states routed through the Timor and Arafura Seas. 

Even on its own, democratic Indonesia, with a population of 280 million, a robust GDP of $1.3 trillion, an active military of over 400,000, and a historical suspicion of China, is a natural obstacle to Beijing’s aspirations in Southeast Asia. In January of 2018, U.S. Secretary of Defense James Mattis described Indonesia as a “maritime fulcrum” in East Asia. In November of 2024, President-elect Donald Trump had a very positive conversation with Indonesia’s new President, Prabowo Subianto, who had received his staff officer training in the United States in the 1980s.   

U.S. aircraft carriers are the cornerstone of the blue water navy and guarantors of trans-oceanic commerce. Diverting these capital platforms to enforce a close blockade of the Chinese littoral in the event of a multi-year war over Taiwan is risking the United States’ preeminent great power status. A network of usable airbases already being constructed in the Philippines, such as at San Vincente Naval Airfield, are less than 600 kilometers from the Taiwan Strait and are a far more cost-effective staging area from which to interdict a Chinese amphibious crossing with combat aircraft and drones. At these distances, U.S. Air Force aircraft will be able to operate with maximum bomb load-outs and without the need for refueling. They will also benefit from the radar masking of their approach by Taiwan’s central mountainous ridgeline. 

China’s principal anti-carrier systems are its estimated thirty 1,800 km range DF-21D missiles and approximately 140 4,000 kilometer range DF-26 anti-ship ballistic missiles, plus an H-6 bomber carried DF-21 variant in development, with a reaction time of less than twenty-five minutes. China’s Type 055 Renhai destroyer can also deliver the 1,000-kilometer range YJ-21 hypersonic anti-ship ballistic missile. A 2,000-kilometer range system will cover Luzon, the Strait of Malacca, and all of the Bay of Bengal, problematizing the use of U.S. carriers there to enforce a blockade, and a 4,000-kilometer range system will encompass Guam, all of Indonesia, and the Central Indian Ocean. 

On September 25, 2024, China launched an 11,500-kilometer-range DF-31AG ICBM into the Pacific for the first time since 1980. This may have been a test of China’s space-based surveillance system to track surface ships. The low probability of a successful strike on a U.S. aircraft carrier increases substantially over the course of an entire blockade campaign, as weather, accidents, miscommunications, chance satellite observation, submarine interceptions, and electronic detection turn a possibility into a high aggregate cost probability of a disabling and subsequent sinking.

While unlikely to be decisive, like any form of sanctioning or interruption of trade, a complete naval blockade of China will contribute significantly to war termination by disrupting China’s export trade, which has grown from $2.2 trillion in 2013 to $3.3 trillion in 2023. Most of China’s imports of $2.16 trillion, 80 percent of its oil, and 90 percent of its overall trade are moved by ships. China is aware of its vulnerability to a blockade and has taken measures to achieve energy and food self-sufficiency. Beijing plans to double its fleet of nuclear reactors to 150 by 2035. 

By cultivating trade and connecting infrastructure to Russia through its overland route, Moscow will be able to provide oil, gas, grain, and key military technologies, even if Washington has the political will to bar the Bering Strait passage to Moscow’s tanker fleet. Beijing has passed legislation requiring local authorities to take responsibility for food reserves, as well as other measures promoting greater domestic productivity. China projects a further 16 to 30 percent increase in caloric demand by 2050 from the growth of its middle class. Of China’s $235 billion in food imports, its three principal suppliers of its largest commodity, soybeans, are Brazil, the United States, and Argentina.

The closure of Indonesia’s Strait of Malacca, through which passes $3.5 trillion in trade aboard 80,000 ships annually, like the 1967 closure of the Suez Canal, would impose an extra monthly re-routing of shipping cost of $2.8 billion, not including the increased cost of insurance. One-third of the world’s shipping, including 23.7 million barrels of oil per day and a substantial portion of the trade of the littoral Asian democracies, transit through the adjacent South China Sea. Needless to say, a war over Taiwan will severely disrupt global supply chains.

Indonesia’s four main straits are easily interdicted by boarding teams carrying patrol ships and helicopters and mobile land-based anti-ship missile platforms. The Strait of Malacca is only 2.7 kilometers wide at its narrowest choke point. The other three principal straits, from west to east, are the ten kilometers wide Sunda, the twenty kilometers wide Lombok, both of which were blocked by Indonesia in 1988, and the ninety kilometers wide Makassar. Other straits further east are the ninety-kilometer-wide Lifamatola, the thirty-five-kilometer-wide Wetar, the thirty-kilometer-wide Ombai, and the 20-kilometer-wide Dampier. 

According to the 2024 International Institute for Strategic Studies’ Military Balance, excluding frigates and coast guard equivalents (Bakamla and KPLP), Indonesia’s available strait policing forces consist of eight Exocet and sixteen torpedo-armed corvettes, fifteen missile-armed patrol craft (out of 159 patrol vessels), eight mine countermeasure ships, drone-ships, eleven Panther and eight AH-64 Apache helicopters, and about thirty maritime patrol aircraft. Given the narrowness of most of the straits, even an instrument as extreme as the use of nuclear weapons could not undo a land-based Indonesian blockade. 

Beijing’s option of directly seizing the Strait of Malacca would be possible but complex. Unlike Japan’s sweep through Southeast Asia in 1941, the major powers, including the United States, have been careful not to become irretrievably committed to conflicts elsewhere in Ukraine and the Middle East. China has six Marine Brigades, a Naval Special Forces Brigade, and six Army Marine brigades, totaling some 40,000 troops. This presumes China would then train new substitute army formations for an amphibious assault on Taiwan. 

Because China’s supply line through the South China Sea would be so precariously exposed to aerial interdiction, even supposing a neutral Vietnam, it would be necessary to seize the airfields of Western Taiwan, Luzon, Palawan, Natuna Island, and several hundred kilometers of Sumatra’s east coast. China would only need to land at Lingayen Gulf and defeat the Philippines’ under-armored 5th and 7th Divisions to neutralize the airbases in northern Luzon and push to Manila. 

Any prospect of securing the 800-kilometer Malacca Strait would require a diplomatic victory to obtain Malaysia and Singapore as bandwagoning allies of a Chinese attack against U.S. interests. A PLAN (People’s Liberation Army Navy) landing would still confront three Indonesian maneuver brigades and four brigade equivalents of battalions, backed up by two Kostrad strategic reserve divisions in Java. 

The United States, Australia, and Japan have anticipated this possibility and have since conducted joint exercises with Indonesia on Sumatra. In November 2023, the United States and Indonesia announced a Joint Comprehensive Strategic Partnership aimed at improving maritime cooperation and as a lead-in to the signing of a future Defense Cooperation Arrangement. Accordingly, Jakarta is in negotiations for the purchase of 24 F-15EXs and additional F-16s. 

At the same time, Jakarta’s relations with Beijing have worsened since China extended its territorial claims to the Exclusive Economic Zone of Indonesia’s Natuna Island. To comply with U.S. investment tax incentives, Indonesia has further imposed high tariffs on a number of Chinese imports and decreased Chinese shareholding in Indonesian nickel-mining concerns (the world’s largest reserves) related to electric vehicles. 

Indonesia, after General Suharto’s 1965 counter-coup against the Communist-influenced Sukarno regime, was a key Cold War ally, securing East Timor from Soviet domination, which had befallen other newly independent Portuguese colonies. Indonesia also plays a useful counter-balancing role against the influence of China, primarily because of its size, in Malaysia and Singapore. Current Malaysian prime minister Anwar Ibrahim has criticized Western hostility to the rise of China, tilting Kuala Lumpur towards Beijing as it seeks its economic investment. 

In a 2022 poll, 39 percent percent of Malaysians viewed China favorably. Singapore, whose 75 percent Chinese population is deeply sympathetic with China, was 67 percent favorable towards Beijing in a 2022 Pew Research Center poll. Although Singapore has shared a Defense Cooperation Agreement with the United States since 2015, providing basing for U.S. LCSs and P-8s, its principal strategy of hedging makes it liable to shift its support to Beijing if the United States appears weak.

Washington’s influence is, however, limited by Jakarta’s policy of non-alignment. Indonesia, Malaysia, and Singapore have all resisted U.S. efforts to subject the Strait of Malacca to international administration. China remains the largest trading partner with all of ASEAN as well as Indonesia and is a major contributor to a $132 billion industrial project and hydropower plant in Kalimantan. Indonesia is also torn between coordinating its response to China with India and privileging its historical alliance with Pakistan, an ally of Beijing.