More than 1,100 F-35 Lightning II stealth aircraft have been delivered to over a dozen countries, with many others awaiting the jets. Most of these countries are either NATO members or strategic US partners. Some of them also have long-standing disputes with China, such as South Korea and Japan.
The US alone uses more than 600 F-35s. According to a recent US government report, the F-35 plays a crucial role in the country’s national security, as well as in safeguarding the US allies and partners.
“The F-35 Joint Strike Fighter plays a crucial role in national security for the U.S. and its partners and allies. The aircraft’s unique stealth technology and advanced sensor networking systems provide critical capabilities to DOD’s tactical air portfolio,” said a US Government Accountability Office (GAO) report released on September 3.
However, supply chains based in China, the strategic competitor of the US, are central to the F-35 upgrade program, giving Beijing a powerful chokehold over the F-35 upgrade program, also known as the Block 4 upgrade, endangering the national security plan of not only the US, but its allies and partners as well.
Crucially, the F-35 Block 4 upgrade program is already suffering from repeated delays and cost overruns, and China’s control of rare earths and metals could be a contributing reason, according to industry assessments.
The F-35 Block 4 Upgrade Program
Since F-35’s induction into the USAF service in 2015, the stealth aircraft has consistently improved its capabilities through upgrades named blocks, ranging from 1A to 3F.
In 2019, the US Department of Defense (DoD) launched its most ambitious F-35 upgrade, the Block 4 upgrade initiative, to improve the fifth-generation aircraft’s radar capabilities, air-to-air engagement range, and precision strike capabilities with the integration of more advanced AAMs.
However, the program has faced repeated delays and cost overruns. Initially, all 66 capabilities under Block 4 were scheduled to be fully deployed by 2026. This timeline was later pushed to 2029.
However, the GAO report released earlier this month warned that Lockheed Martin will not be able to deliver the Block 4 upgrade, even with only a “subset of the original 66 … capabilities,” by 2031, five years later than the initial timeline.
The report also highlighted the cost overruns in the Block 4 upgrade program.
“Currently, Block 4 costs are over US$6 billion more, and completion is at least 5 years later than original estimates,” the GAO report said.
Notably, as per the GAO report, while in 2023, Lockheed Martin delivered F-35s with an average delay of 61 days, by 2024, the average delay in F-35 deliveries was 238 days.
A major cause for these delays was Lockheed Martin’s Technology Refresh 3 (TR-3), a US$1.9 billion package of hardware and software upgrades essential to the Block 4 modernisation.
However, given China’s near-total chokehold on rare earth elements, which are crucial for the F-35’s Block 4 upgrade, in the future, the F-35 deliveries can face further delays and cost overruns.
How China Can Delay F-35 Block 4 Upgrade
While the GAO report did not specify the reasons for the F-35 delays, according to some analysts, a significant reason could be China’s total control over rare earth elements and the restrictions Beijing has imposed on their exports to the US.
For instance, one planned upgrade under the Block 4 initiative involves a new radar system called AN/APG-85 that uses gallium nitride (GaN) antenna elements.
GaN technology allows for higher power output, better thermal management, improved efficiency, and increased durability compared to older Gallium Arsenide (GaAs) technologies. This leads to greater detection ranges and enhanced resistance to jamming.
“Compared to traditional gallium arsenide (GaAs), GaN offers notable advantages: it supports power densities five to 10 times higher than GaAs, greatly enhancing radar detection range and resolution,” according to a recent report by the Chinese Academy of Sciences’ Institute of Physics.
“Radars made with GaN are more compact and efficient, with stronger reliability and longer service life in high-temperature environments, substantially reducing maintenance needs and costs,” the report said.
The report further said that China’s growing dominance in gallium nitride (GaN) semiconductor technology gives it a strategic advantage that is reshaping the global arms race and has the potential to delay the F-35 Block 4 upgrade initiative.
China’s restrictions on the export of critical raw materials like gallium and germanium are adversely impacting the production of next-generation military electronics in the US.
Consequently, the US is already possibly a generation behind China in the development and adoption of the next generation of phased array radar systems across military platforms such as fighter jets, missiles, tanks, air defense systems, and naval warships.
China is one of the world’s largest producers of alumina, which gives it a natural advantage in large-scale gallium extraction, a by-product that often occurs alongside bauxite and lead-zinc ores.
According to the US Geological Survey, as of 2022, China accounted for about 68 per cent of the 279,300 tonnes of global proven reserves of gallium metal – the highest share worldwide.
Additionally, China also has highly mature technologies for gallium refining and processing, accounting for more than 90 per cent of global refined gallium production in 2023.
Notably, China has imposed export controls on gallium and germanium since 2023. These export restrictions were further strengthened in December 2024.
Another report released in April this year underlines how rare earth elements were fundamental to advanced US military platforms such as the F-35 Lightning II fighter jet.
The report released by the Washington-based think tank, the Center for Strategic and International Studies (CSIS), explains that a single F-35 contains more than 900 pounds of rare earths.
“REEs (Rare Earth Elements) are crucial for a range of defense technologies, including F-35 fighter jets, Virginia- and Columbia-class submarines, Tomahawk missiles, radar systems, Predator unmanned aerial vehicles, and the Joint Direct Attack Munition series of smart bombs,” the CSIS report said.
“The F-35 fighter jet contains over 900 pounds of REEs. An Arleigh Burke-class DDG-51 destroyer requires approximately 5,200 pounds, while a Virginia-class submarine uses around 9,200 pounds,” it added.
Furthermore, according to The New York Times, Lockheed Martin is the largest American user of samarium, another rare earth element, with each F-35 incorporating about 50 pounds (22.6kg) of samarium-cobalt magnets.
Notably, China produces the entire world’s supply of samarium, a particularly obscure rare earth metal used almost entirely in military applications. Samarium magnets can withstand temperatures hot enough to melt lead without losing their magnetic force.
They are essential for withstanding the heat of fast-moving electric motors in cramped spaces like the nose cones of missiles.
“The main American user of samarium is Lockheed Martin, an aerospace and military contractor that puts about 50 pounds of samarium magnets in each F-35 fighter jet,” the NYT report said.
REEs are also critical for the radar absorbent coating on F-35s, which is crucial for its stealth characteristics. Additionally, REEs are also used in the AAMs carried by the F-35.
Apart from GaN and samarium, a host of other REEs, such as yttrium, dysprosium, and terbium, are critical to various core systems of the F-35.
According to the CSIS report, as of 2023, China accounted for 99 percent of global heavy REEs processing, with only minimal output from a refinery in Vietnam.
“However, that facility has been shut down for the past year due to a tax dispute, effectively giving China a monopoly over supply,” it added.
China has introduced a license and quota system for exporting these REEs, allowing Beijing to supervise the end users of these critical magnets.
China’s chokehold on these REEs can further delay the Block 4 upgrade initiative for the F-35, compromising the defense preparedness of not just the US but also of its allies and partners.
