The head of the U.S. government’s F-35 fighter program on Wednesday said efforts to trim costs on the world’s most expensive weapons contract hinged in part on looming procurement decisions by Italy, Turkey and Canada.

Lt. Gen. Christopher Bogdan, head of the Pentagon’s F-35 program office, said foreign partners are closely watching efforts to resolve continuing technical problems. Any changes to existing commitments by Italy and Turkey to buy the jets—or any move by Canada to secure an alternative plane—could inflate the aircraft’s cost for all buyers by 2% to 3%, he said at a congressional hearing.

The F-35 currently sells for more than $100 million each, excluding research and development costs. The Pentagon and the F-35’s main contractor, Lockheed Martin Corp. , are trying to reduce the production and operating costs of the jet to make it more affordable to domestic and overseas customers. […]