Bern and Washington are quibbling over the final price of the new planes bought to replace the ageing Swiss fleet.

The US Defense Security Cooperation Agency wants Switzerland to assume additional costs, but Bern says it is sticking to the agreed price of just over six billion Swiss francs ($7.65 billion at current exchange rates).

The DSCA, through which the planes are bought, says Bern should bear potential additional costs of $650 million to $1.3 billion caused by high inflation in the United States in recent years, and increases in raw material and energy prices.

"The National Council's Audit Committee has decided to investigate the authorities' management of the issue of the fixed price for the F-35A procurement," it said in a statement.

The inquiry will also look at how the seven-member Federal Council government handled expert reports on the price, and the information the government provided to the parliamentary oversight body and to the public.

"In light of the latest information regarding a possible price increase for the F-35A, the committee has re-examined the issue and reassessed the situation," it said.

"It has decided to seek to determine whether, in retrospect, any shortcomings could be identified in the Federal Council's handling of the contract negotiations."

Bern is seeking a diplomatic solution to the dispute.

The government won a referendum in September 2020 by a razor-thin margin that approved the military spending six billion Swiss francs on a new fleet.

The F-35A combat aircraft, used by the US Air Force and several European countries, was chosen in June 2021 over the Airbus Eurofighter, the F/A-18 Super Hornet by Boeing, and the Rafale from French firm Dassault.

The contract was signed in September 2022, when six billion Swiss francs was the equivalent of $6.2 billion.

The first deliveries are due in 2027.

Switzerland's long-standing position has been one of well-armed military neutrality, and the country has mandatory conscription for men.

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LOCKHEED MARTIN

BOEING

Dassault Aviation