WASHINGTON (AFP)--The U.K. on Wednesday formally agreed to purchase three F-35 Joint Strike Fighter aircraft for initial testing, Defense Minister John Hutton confirmed during a visit to the U.S. capital.

"I've also got some good news today for the U.K.-U.S. special relationship," said Hutton, announcing the deal alongside U.S. Defense Secretary Robert Gates.

He said the U.K. would be "fully participating" in the development stage of the F-35 and that the aircraft would form "a very big part of the future for the Royal Air Force."

Lockheed Martin Corp.'s (LMT) supersonic aircraft is designed to evade radar and replace aging fighter aircraft for the U.S. military and eight other allied countries.

The meeting between the two defense chiefs mainly focused a U.S. strategy review for the war in Afghanistan, Gates told reporters.

The results of the review are expected to be announced within days, defense officials say.