Media: US, Japan plan world’s deepest undersea mine to challenge China

The United States and Japan are moving ahead with plans to develop what could become the world’s deepest undersea mining project, targeting rare earth deposits about 6,000 metres beneath the Pacific Ocean near Japan’s remote Minamitorishima island, Bloomberg reports. 

The initiative is aimed at reducing both countries’ dependence on China for critical minerals.

The deposits are believed to contain more than 16 million tonnes of rare earth minerals, including heavy rare earths such as yttrium, dysprosium, gadolinium and terbium. These materials are essential for products ranging from semiconductors and electric vehicle motors to high-performance magnets and missile guidance systems.

Japan has already conducted test extractions from the seabed and recently reported significant concentrations of several heavy rare earth elements. Further drilling is planned, with Tokyo targeting a commercialisation plan by 2028. A full-scale mining test lasting one month is scheduled for February 2027 and is expected to include refining and smelting.

The project faces major technical and financial challenges. The deposits lie at a depth roughly twice that reached by existing offshore oil drilling projects, while water pressure is about 600 times higher than at sea level. One private-sector estimate puts the cost of producing the minerals at roughly three times that of land-based extraction in China, with billions of dollars potentially required over more than a decade.

Despite these obstacles, Japan views the project as strategically important. Prime Minister Sanae Takaichi has made reducing reliance on China a central part of her economic security policy. Her long-term growth strategy envisages about $5.7 billion in public and private investment in deep-sea resource development by 2040.

Washington has also increased its interest following China’s restrictions on rare earth exports. US President Donald Trump ordered federal agencies in April to accelerate reviews and licensing for deep-sea mining projects in the US and abroad. The two countries signed a memorandum of understanding on deep-sea mining following Trump and Takaichi’s March meeting.

Several North American companies have shown early interest, including Houston-based Deep Reach Technology, which has held initial discussions with Japanese officials. The company is already involved in a separate seabed project in the Minamitorishima exclusive economic zone.

China’s growing activity around the area has added urgency to the initiative. Chinese oceanographic vessels have conducted surveys near Japan’s exclusive economic zone, while a Chinese aircraft carrier entered the zone in June 2025. Tokyo subsequently strengthened surveillance and defence measures around the remote island.

William Chou of the Hudson Institute said the project could allow the US and Japan to develop a complete rare earth supply chain outside China. “You can make the argument that the American enthusiasm for Minamitorishima is also part deterring China and trying to convince them that ‘We are not entirely reliant on you,” Chou said. “We have options, too.’

By Aghakazim Guliyev