The Pentagon decided to focus on using additional funding to upgrade the F-35 with new capabilities every six months. The Pentagon is focusing on using additional funding to upgrade the F-35 with new capabilities every six months

WASHINGTON - The Biden administration will seek US$11 billion (S$14.7 billion) to buy 85 Lockheed Martin F-35 jets in the coming fiscal year, tracking a plan outlined last year by the Trump administration, according to a United States official.

With a US$715 billion budget request for fiscal year 2022, the Pentagon had considered increasing the quantity of next-generation fighters it planned to buy, but decided to instead focus on using additional funding to upgrade the F-35 with new capabilities every six months, the official said.

"It's not unusual for a new administration's first budget to change relatively little from its predecessor," Mr J. J. Gertler, a military aviation analyst for the non-partisan Congressional Research Service, said in an e-mail.

"But using the prior number for FY22 adds fuel to the idea that the big changes for the programme will come in '23," he said.

At an estimated cost of US$398 billion, the F-35 is America's biggest weapons programme, a critical part of US and allied efforts to upgrade their armed forces.

Yet while the US$715 billion defence budget number is public, the Pentagon has not yet detailed how that will be spent and there is no formal release date yet from the Office of Management and Budget.

The Defence Department "will respond to questions on the specifics of the budget request after it is submitted", Ms Laura Seal, a spokesman for the department's F-35 joint programme office (JPO), said in an e-mail.

The "JPO doesn't have anything to provide in advance".

The number of F-35s sought by the administration, as well as spending on upgrades to the nation's nuclear arsenal, the navy shipbuilding budget and questions over whether the army will absorb major cuts to its modernisation plans will be the most scrutinised issues in President Joe Biden's first defence budget.

Of the 85 jets, 48 will be requested by the air force, sticking to last year's plan, according to the budget data.

The so-called Block 4 upgrade programme on the F-35 has largely escaped public scrutiny while the jet continues to grapple with other issues.

Those include a major delay in completing combat testing, uncertainty over when a decision authorising full-rate production will take place and growing concerns about the jet's roughly US$1.72 trillion "life-cycle" cost, which include acquisition and maintenance and operations over decades.

The Block 4 upgrade programme's US$14 billion estimated cost is more expensive than many army, navy and air force acquisition programs.

With the F-35 essentially a flying computer, keeping the jet's upgrades on track and adequately funded are more important to the Biden Pentagon than increasing quantities of current model aircraft that will need to be eventually upgraded, Ms Stacy Cummings, the acting undersecretary for acquisition and sustainment, told a Senate Armed Services sub-committee last month in written testimony.

Upgrading the F-35's hardware and software systems "through the Block 4 modernisation effort is critical for ensuring our war fighters remain equipped with the best tools available", Ms Cummings wrote.

"The department has prioritised modernisation to keep these capabilities on track, working to provide a stable, realistic funding baseline," she said.

"Accelerating or increasing procurement quantities" of earlier F-35 variants "is counterproductive and wastes scarce resources as such planes will need to be pulled from the flight line and retrofitted when Block 4 capabilities deliver", she added.

Among the Block 4 areas that need additional funding, US taxpayers and allied partners are absorbing a US$444 million overrun caused by Lockheed Martin sub-contractor issues on a key hardware upgrade, called TR3, that is the first step to increasing the power and memory of the jet.

Ms Jessica Maxwell, a Pentagon spokesman, said in a statement that "the budget must balance many factors to ensure our military can meet national defence objectives now and in the future".

The department "remains committed to using taxpayer dollars responsibly and acquiring F-35s as affordably as possible while also meeting current war fighter needs", Ms Maxwell said.