The Swiss government is seeking more talks with the United States after a last-gasp mission to the US capital failed to stop a 39-percent tariff blow that businesses described as a "horror scenario".

"Military purchases are important for relations with the United States," Pfister told Switzerland's domestic Keystone-ATS news agency.

"However, we must first find a path for discussion with the Americans" to try to move relations forward overall, he said.

US President Donald Trump blindsided the Swiss when he announced that the wealthy Alpine nation would be hit by one of the highest tariffs among new duties on imports from dozens of economies that took effect on Thursday.

The tariff jeopardises entire sectors of the export-heavy Swiss economy, notably watchmaking and industrial machinery, but also chocolate and cheese.

Swiss businesses worry that competitors in other wealthy economies will have an edge, with the European Union and Japan having negotiated a 15-percent tariff and Britain securing a rate of 10 percent.

Switzerland has argued that the United States enjoys a significant services trade surplus and that most US industrial goods enter Switzerland tariff-free.

Pfister stressed that the government had decided not to call into question Switzerland's current contract to buy 36 new Lockheed Martin F-35A fighter jets.

"The issue of the fixed price remains to be resolved," he added.

Switzerland and the United States are quibbling over the final price of the F-35As 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 ($7.4 billion).

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

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