Operation Highmast got underway in late April, as the British aircraft carrier HMS Prince of Wales and supporting warships embarked on an eight-month deployment, also known as Carrier Strike Group 25, to the Pacific and Australia.

Highmast is the biggest test to date for the Royal Navy’s return to the carrier business, a plan 30 years in the making. At least in theory, this renewed British power-projection capacity offers to support the United States in the Pacific—if not by deploying there in a crisis and joining in the fighting, then maybe by relieving the US of duties in the Middle East.

Yet the British carrier force faces obstacles. The only kind of fighter that the carriers can operate is the F-35B, which can make short take-offs unassisted by a catapult and can land vertically, not needing arrestor wires. Britain doesn’t have enough F-35Bs, and there’s a serious risk that the price of buying them will rise steeply.

Meanwhile, the ships rely on helicopters for carrying air-surveillance radars aloft, whereas some kind of aeroplane, with greater altitude and endurance, would be far better for the task.

Unlike a Pacific deployment of sister ship HMS Queen Elizabeth four years ago, Highmast includes only British F-35Bs; 18 are aboard Prince of Wales. Last time, 10 of the 18 F-35Bs were guests from the US Marine Corps.

The latest carrier group is in uncharted waters. Prime Minister Sir Keir Starmer’s Labour government is still new after 12 years of Tory rule, and a strategic defence review is under way. Ukraine and Donald Trump have combined to form the second up-ending of strategic assumptions since Britain’s first strategic defence review committed to building the carriers in 1998, and British defence equipment plans (as usual) require more money than is available.

The RN is irreversibly committed to carriers and what carriers do, which—as admirals Yamamoto and Halsey showed in the Pacific eight decades ago—is to project power at great distances.

But what do you do when an enemy rises from its tomb in the middle of your neighbouring land mass? At least some British defence planners must be thinking that aircraft carriers aren’t needed for facing Russia.

The two carriers are an achievement, far from poor relations of the American nuclear ships. British naval architects recognised that the life-cycle cost of a carrier was dominated by people, as did the US Navy in the early days of development of its new Ford class, but the RN did something about the issue, with highly automated turbine-electric engine rooms and robotic weapon handling.

The snag is that an aircraft carrier carries aircraft. Its offensive and defensive weapon is its air wing, and at present the RN air wing has a gaping hole.

There is no substitute for airborne early warning for any warship fleet. Unprepared in the Falklands in 1982, the RN bodged a solution by fitting Sea King anti-submarine helicopters with an off-the-shelf radar. The concept worked better and lasted longer than expected, but the RN seems to have pushed it too far in its latest iteration, Crowsnest, which uses a 2000s-era radar on the Merlin helicopter. Just declared operational, Crowsnest already has an end-2029 out-of-service date. So let’s not count it as a satisfactory solution.

The RN is planning to use uncrewed aeroplanes  to provide airborne early warning. One option under study is to carry a radar pod on a variant of the General Atomics MQ-9 family; the version would have a modified wing giving high lift and better low-speed control so it could take off and land on the British ships, which lack catapults and landing arrestor gear. The MQ-9s could take-off just by rolling forward into the wind, and they’d land slowly enough to stop with their brakes.

A smaller, related uncrewed aircraft, General Atomics’ Mojave, was tested on Prince of Wales in 2023—but there is a lot of expensive work left to do.

Although Prince of Wales sailed with only 18 F-35Bs aboard, six more may fly out to the ship later in the exercise. Getting those 24 together is a stretch for Britain, which has a usable F-35B fleet of 33 out of 37 units delivered (one lost and three assigned to tests in the US) and 11 on order.

Something may have been learned from the deployment of the Queen Elizabeth in 2021, where fatigue was cited as a factor in the loss of an F-35B that crashed. In operation Highmast, the ratio of air group personnel to aircraft is higher.

Britain’s F-35s lacks two missile types that have been intended for them, the intended MBDA Meteor ramjet-powered air-to-air missile and Spear 3 air-to-surface weapon. The F-35 should carry eight Spears internally, with a standoff range of more than 100 km. The weapon itself is running behind schedule, making its first guided test flight in November, and there is no set date for integration of either Spear or Meteor on the F-35. And there won’t be one before the Joint Strike Fighter program office can set a revised schedule for the F-35’s troubled Block 4 upgrade effort. The previous plan was discarded in early 2024. A contributing factor is a shortage of instrumented test assets, not helped by the loss last May of one of the test force’s newest F-35Bs.

But there is a looming cloud on the horizon of the F-35B, the only modern fighter than Britain’s aircraft carriers can now use. A new US Marine Aviation Plan published in January disclosed that the US Navy plans to change intended orders for 73 F-35Bs to F-35Cs, designed for catapult-launch and arrested recovery on aircraft carriers. This would leave only 60 more F-35Bs to be delivered to the US after FY2025 and put upward pressure on the F-35B unit cost. It’s already $175 million in the current budget. And the British Ministry of Defence has determined that it needs another 26 Bs, a total buy of 74, to support carrier squadrons.

Lockheed Martin has been pitching a radical proposal to Britain: convert the carriers to catapult-and-arrest configuration in the early 2030s and buy F-35Cs plus a gap-filler land-based fleet of either F-35As or fighters of an advanced land-based F-35 variant. Whether or not it gains traction in Britain, this idea doesn’t indicate confidence in the future of the F-35B.

Then, in written pre-confirmation testimony, new US Navy Secretary John Phelan was asked directly how many Marine F-35Bs would not get Block 4 upgrades, and responded noncommittally that ‘clear requirements for a potential Block 4 upgrade’ were still being defined.

The F-35B exists only because of the US Marine Corps’ outsize political influence. Neither is it a secret that there are few F-35B fans in big-carrier US naval aviation: the version is expensive and doesn’t contribute a lot of capability to a US task group. ‘Marine aviation has always the annoying little brother,’ a US Navy aviator told me some years ago, ‘but now they’re getting expensive.

Diminishing support for the F-35B and the high cost of alternatives are not happy news for Britain’s carrier force.