When Sir Keir Starmer jetted into Tokyo for his first visit, the Prime Minister claimed Britain’s relationship with Japan was now “the strongest it has been in decades”.
“The UK-Japan partnership is of profound and growing importance,” he told his hosts, flanked by close allies including Jonathan Powell, the national security tsar, and Peter Kyle, the Business Secretary.
“Like you, I believe Euro-Atlantic security and Indo-Pacific security are indivisible.”
Yet five months later, as Sanae Takaichi, Sir Keir’s Japanese counterpart, prepares to visit the UK this weekend, cracks are appearing in this rosy façade.
For some time, tensions between Tokyo and London have been growing over the global combat air programme (GCAP): the joint UK-Italy-Japan project to develop a next-generation stealth jet.
The programme, known as Tempest domestically, aims to develop a long-range strike aircraft and have it in the air by 2035. It will cost tens of billions of pounds, with Britain’s share expected to come to at least £12bn over a decade.
But officials in Tokyo have become frustrated in recent months with Starmer’s failure to match words with actions, as London pushes to delay an injection of cash.
A computer-generated image of the proposed Tempest combat jet – Ministry of Defence
The three countries originally aimed to sign a contract providing long-term funding for Edgewing, the joint venture that has been set up to execute the GCAP programme, by the end of last year.
Instead, as British ministers wrangle over how to plug a £28bn funding shortfall for a domestic equipment pipeline known as the defence investment plan (DIP), the deal has been repeatedly pushed back.
To stop the project running out of money, the partners signed a temporary three-month contract in April – but that will expire at the end of this month.
It has prompted a series of complaints behind the scenes from Japan, while officials have grumbled privately that Britain is becoming a “ghost ally”.
“The Japanese thought the Italians were going to be the problem,” says Francis Tusa, an independent defence analyst. “But actually, it turned out to be the Brits.
“If we screw this up, there will be hell to pay. It could be a disaster for our alliances in Asia.
“Japan would rightly tell people: ‘Don’t touch them with a bargepole.’”
The Government’s repeated delays have reportedly caused tension with Japan – YUICHI YAMAZAKI/REUTERS
To understand how the Ministry of Defence (MoD) got into such a mess, it pays to look at why GCAP is different from other military programmes.
Britain signed an international treaty to establish GCAP with Japan and Italy in 2023.
That was meant to underline the deep and binding commitment the three countries were making to the programme.
Yet since then, the Government has at times looked like it wants to wriggle out of its responsibilities rather than meet them.
For months, British ministers have prevaricated over funding – tying GCAP’s future to the fate of the DIP and refusing to give the programme their full-throated backing.
Earlier this month, The Telegraph revealed the Treasury had even floated the idea of delaying Britain’s spending on GCAP until the 2030s.
This betrayed a fundamental “misunderstanding of the nature of GCAP” inside the Government, says Tusa, as well as a failure to appreciate the importance of the project to Japan.
International treaties are a serious business, he argues, because they put Britain’s good word on the line. But for security reasons as well, delaying the funding into the 2030s is simply a non-starter.
In public statements, the UK, Japan and Italy have repeatedly said they want to get the new stealth jet into the sky by 2035 – a timeline that looked highly ambitious even before Britain’s stalling.
You cannot build a next-generation aircraft in just a few years. Serious cash injections are needed now to ensure that aircraft will be flying by the target 2035 date, points out Tusa.
He also says that for Tokyo, delivering GCAP by that year is not simply a ‘nice-to-have’, but rather a national imperative.
Japanese officials are watching with alarm as China becomes an increasingly belligerent neighbour, claiming sovereignty over the South China Sea, menacing Taiwan and making incursions into Japanese-controlled territories.
In response, they have vowed to step up Japan’s own military capabilities to create a powerful deterrent for Beijing – with GCAP at the heart of these plans.
This is why suggestions of delays to the programme have been met with so much concern by officials in Tokyo.
It is simply not possible to push back the funding while still delivering the programme on time, according to insiders.
“Delaying the funding until the 2030s is not an option,” says one person close to the programme. “You either do it now, or you don’t do it at all.”
Others have warned that the UK could seek to roll over GCAP onto another three-month contract extension.
Starmer is said to have set a “hard deadline” of July 7, when a Nato summit is due to take place, for the DIP’s publication, although some insiders have suggested it could be published as soon as this Thursday.
But worries about further delays have reportedly prompted Japanese officials to make complaints, including to Yvette Cooper, the Foreign Secretary, on her recent trip to Asia.
One person also claimed Tokyo had even suggested Japanese investment in the UK and an expected forthcoming visit by Takaichi could be at risk.
The Japanese embassy in London insists there is “no truth” to these claims – but has yet to publicly commit to Takaichi’s potential visit, which was reported in Japanese media.
“Negotiations regarding the contract… are currently underway and the governments of Japan, the UK and Italy are working closely together to secure a long-term agreement,” an embassy spokesman said.
“As regards prime minister Takaichi’s overseas visits, nothing has been decided at this stage, and there is no truth to claims that Tokyo has informed Downing Street to call off the visit to the UK on the grounds of GCAP.”
Starmer is said to have set a ‘hard deadline’ of July 7 in line with a planned NATO summit – Henry Nicholls/PA Wire
At the same time, Donald Trump, the US president, is reportedly trying to persuade Tokyo to jump ship and throw its lot in with America instead.
It has piled extra weight on to Starmer’s decision that goes beyond domestic budget constraints. At risk, argues defence analyst Tusa, is Britain’s standing with key allies.
“Of course we can say we have domestic issues, but that’s no excuse,” he says. “The Japanese and the Italians have their priorities as well.
“I worry that the lesson the Treasury will take from this is not to sign international treaties, because they bind you. But that’s supposed to be the whole point.”
This is the central dilemma facing Starmer’s Government, with no easy answers available.
The funding for GCAP will reportedly require an immediate commitment of £6bn, but the MoD has previously estimated it could cost more than £12bn over a decade.
Finding that cash will require ministers to resolve a £28bn funding shortfall for the DIP, which is likely to mean painful cuts elsewhere.
To free up cash, the Government is considering cuts to capital projects in net zero, transport, military housing and NHS hospitals, according to The Sunday Times.
Rachel Reeves, the Chancellor, is said to have dug in for a fight with the Ministry of Defence, which the Treasury regards as a delinquent department that cannot stick to a budget.
A spokesman for Edgewing says GCAP bosses have “full confidence that additional funding will be allocated” in the forthcoming plan.
Yet further delays to GCAP will probably cost more than just money. As he seeks to shore up Britain’s alliances, Starmer may find his words buy less than they used to as well.