Japan made waves last February when it extracted sediment rich in heavy rare earths from the seafloor almost 6,000 meters down. But can deep-sea mining break China’s near monopoly on these critical minerals?
Rare Earth Recovered from Deep Seabed
In February 2026, a research team under the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) succeeded in extracting rare-earth-rich mud from the seabed off the remote Japanese island of Minamitorishima at a depth of 5,700 meters.
Rare-earth elements (REEs) play a critical role in the technology and economy of the twenty-first century. Used in a wide array of electronics, as well as such eco-friendly power sources as wind turbines and electric vehicle motors, they are vital to the digital and green transformation, the two main engines of sustainable growth. They also have massive implications for national security, given their use in jet fighters, rocket engines, and other military technology.
Today, the global supply of REEs is largely controlled by China, which dominates in both mining and refining (separation of the individual rare earths from the ore). For Japan, the United States, and many other industrially advanced countries, reducing this dependency on China has become an urgent priority. News of the successful test off Minamitorishima has raised hopes that deep-sea mining might offer a path to self-sufficiency. But the technical hurdles to commercialization are high.
In the following, I provide an introduction to the deep-sea rare-earth excavation project launched by the Japanese government’s Cross-ministerial Strategic Innovation Promotion Program and discuss how Minamitorishima’s seabed deposits might contribute to a diversified and reliable supply chain for critical minerals.
China’s Lock on Heavy Rare Earths
The term rare earth elements refers to 17 metallic elements that feature certain chemical and electrical characteristics, such as permanent magnetism. The REEs are further divided by atomic weight into 7 light rare earths, or LREEs, and 10 heavy rare earths, or HREEs. The latter are used in laser and aerospace technologies with advanced military applications and are thus of higher value. While LREE deposits are distributed fairly widely around the world, HREEs are heavily concentrated in China. This is one reason China is able to leverage export controls for strategic purposes.
In April 2025, China imposed strict export controls on seven HREEs, ostensibly to prevent their diversion to military purposes and safeguard national security.
Rare Earths Subject to New Chinese Export Controls
Samarium: Sensors, medical devices, automotive parts
Gadolinium: MRI contrast agents, nuclear reactor control rods
Terbium: Security inks, laser processing
Dysprosium: EV and hybrid motors, wind turbines, data storage devices
Lutetium: Lasers, radiation therapy
Scandium: Electrodes, lasers, aircraft components
Yttrium: Yttrium filters, lasers, superconductors
Compiled by the author from information in Saitō Katsuhiro, Rea metaru, rea āsu no odorokubeki nōryoku (The Amazing Potential of Rare Metals and Rare Earths) (C&R Kenkyūjo, 2019), pp. 216–29.
Government-Driven Innovation
Under Japan’s Cross-ministerial Strategic Innovation Promotion Program (SIP), headed by the Cabinet Office’s Council for Science, Technology, and Innovation, research teams have spent more than a decade on a project dedicated to the domestic production of rare earths, focusing on the seabed off the remote atoll of Minamitorishima, about 1,950 miles southeast of central Tokyo. In the first phase (2014–18), the project targeted hydrothermal deposits at depths of up to 2,000 meters. The second phase (2018–22) focused on development of the technology needed to explore and tap deep-sea resources at depths in excess of 2,000 meters. Beginning in 2023, the results of that research were used to carry out phase 3 (dubbed Construction of a Marine Security Platform).
In phase 3 of the SIP rare-earth project, researchers confirmed that there were REE deposits sufficient for commercial exploitation at a depth of close to 6,000 meters in the seabed off Minamitorishima, within Japan’s exclusive economic zone (EEZ). The deposits contain high concentrations of at least six HREEs on which China has recently imposed export restrictions. Their value to Japanese industry can hardly be overstated.
To extract the REE-rich sediment from deposits roughly three and a half miles underwater, a robot collector was connected to the drilling vessel Chikyū via a riser pipe consisting of 600 segments, each measuring 10 meters long.
The deep-sea mining project can now move on to the next phase, a demonstration trial that aims to excavate 350 tons of rare-earth mud per day in February 2027.
Three Hurdles to Rare-Earth Self-Sufficiency
The February 2026 test extraction was a groundbreaking event, representing the world’s first successful attempt at deep-sea rare-earth mining. But translating this experiment into commercial production will mean grappling with three extremely challenging problems.
The first is developing an environmentally friendly refining process. REE-rich ore typically contains a mixture of rare earths and other elements. The processes currently used to separate them involve the use of various chemicals and generate a large quantity of pollutants, including toxic gases, sludge, and radioactive waste.
As the environmental movement gained momentum in the 1980s, an increasingly strict regulatory climate made it difficult for companies in the industrially advanced world to operate in a cost-effective manner. As a result, countries like the United States and France ceded leadership of the field to China, where regulations were relatively lax.
Japan was no exception. Faced with rising costs, Japanese companies transferred their own sophisticated refining technology to China, which now controls 90% of the world’s rare-earth refining capacity. Toxic waste and by-products are expected to be less of a problem when refining REEs from seabed mud, but getting domestic businesses to join forces in resurrecting and updating their refining technologies will be a major challenge.
The second major hurdle is commercial viability—that is, turning the production of seabed-sourced REEs into a profitable business. Test mining around the remote atoll of Minamitorishima, some 1,950 miles from mainland Tokyo, was conducted at an annual cost of over ¥10 billion, which averages out to tens of millions of yen per day. Japan may be able to establish the world’s first industrial deep-sea commercial mining operation, paired with sustainable refining technology, and large-scale production should bring unit costs down. Even so, the rare-earth materials thus produced will not be able to compete with China’s from a price standpoint.
Finally, there is the question of how to meet the threat of interference from China. In June 2025, the Chinese aircraft carrier Liaoning entered Japan’s EEZ southwest of Minamitorishima, quite possibly with the aim of deterring Japan’s REE exploration efforts. China could also obstruct commercial development by threatening to withhold REE exports from companies that invest in projects off Minamitorishima.
This is the context in which Japan and the United States signed their March 2026 memorandum of cooperation regarding development of deep-sea mineral resources, with specific mention of Minamitorishima. Some in this country may lament the fact that Japan cannot independently pursue the development of mineral resources within its own EEZ. But Japan and the United States share an interest in establishing secure supplies of critical minerals, and if collaboration on deep-sea mining around Minamitorishima can deter Chinese interference, then it makes good sense from a long-term perspective.
Taking the Long View
Given the foregoing, how should Japan go about stabilizing its rare-minerals supply chains so as to bolster economic security?
The Minamitorishima seabed mining project should be pursued as one component of the national policy of diversifying Japan’s rare-earth supply chains. With this in mind, Japan should proceed step by step with the development of commercial mining and refining processes. However it would be wrong to view deep-sea mining off Minamitorishima as a silver bullet.
Japan has already made some progress toward diversification of its REE suppliers, having fallen victim to China’s weaponization of export restrictions as far back as 2012 (when Tokyo aroused Beijing’s wrath by nationalizing the disputed Senkaku Islands). Specifically, Japan has provided financing for Australia’s Lynas Rare Earths, the world’s largest producer of separated REEs outside of China, and inked a major HREE supply agreement with that firm. In 2024 and 2025, Japan concluded deals to help fund French company Caremag’s new large-scale rare-earth recycling facility in return for supply commitments.
As we have seen, seabed mining in the waters off Minamitorishima is no quick fix for the problem of dependence on China, particularly given the obstacles to profitability and price competitiveness. From a long-term perspective, however, boosting Japan’s self-sufficiency in rare minerals is an important means of strengthening the country’s resilience in the face of export restrictions and other international disruptions. From this standpoint, the SIP’s promotion of deep-sea rare-earth production has profound significance for Japanese economic security.
In addition, commercialization of deep-sea mining of REEs would go a long way toward boosting Japan’s stature as a maritime power. Equipped with an environmentally friendly method for extracting rare minerals, Japan would be in an excellent position to assist the region’s island nations with seafloor resource development, thus laying the foundation for closer relations.
With such long-term considerations in mind, I would recommend that Japan continue pursuing the Minamitorishima rare-earth mining project as an important component of the nation’s economic and security strategy.
(Originally published in Japanese. Banner photo: The deep-sea drilling vessel Chikyū, operated by the Japan Agency for Marine-Earth Science and Technology. Image courtesy of JAMSTEC.)