Updated

Norway on Friday ordered the first two fighter jets of an expected combined order of 52 from Lockheed Martin's troubled Joint Strike Fighter program as it embarked on a 2008 plan to replace its aging fleet of F-16 combat aircraft.

Defense Minister Espen Barth Eide said in a statement that the F-35A Lightning II jets are expected to arrive in 2015, with a further 50 aircraft expected to follow two years later at a total cost of 60 billion kroner ($10 billion).

"This marks a key milestone in the Norwegian F-35 program, and the beginning of the largest public procurement in Norwegian history," Barth Eide said.

He added that parliament had authorized the initial purchase on Thursday and the first two jets will be based in the U.S., where they will be used to train Norwegian pilots.

Norway is a funding partner in the Joint Strike Fighter program, which the U.S. Defense Department has described as the largest fighter aircraft program in history.

The program aims to replace a wide range of existing fighter, strike, and ground attack aircraft for the U.S., and eight partner countries: Norway, Britain, Australia, Canada, Turkey, Italy, Denmark and the Netherlands.

The Lockheed Martin Corp. program, however, has been troubled by repeated blowouts in cost as well as delivery schedules.

Critics have also questioned whether the multirole jet offers sufficient improvement in capabilities over existing top-of-the line fighters to justify its extreme unit costs.

Last month, Britain abandoned proposals to buy a particular type of F-35 Joint Strike Fighter because it said the cost of ship modifications to accommodate the F-35c variants would be about 2 billion pounds ($3.2 billion).

The U.S. and Australia have delayed their orders, and the Netherlands has said it will trim its order.

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Jan M. Olsen in Copenhagen and Slobodan Lekic in Brussels contributed to this report.