US Secretary of Defense Chuck Hagel speaks at a news briefing to announce reforms to the nuclear enterprise at the Pentagon in Washington, in a Nov 14, 2014 file photo. [Photo/Agencies]

WASHINGTON -- The US military will divest an air base in Britain and return it and 14 other facilities in Europe back to their home nations, the Pentagon said on Thursday, in a bid to save the US government about $500 million annually.

The restructuring will pull thousands of US military and civilian personnel out of the 15 sites mostly in the United Kingdom and Germany over several years, the Pentagon said in a statement.

The Pentagon would divest RAF Mildenhall, northeast of London, and withdraw 3,200 US personnel from the base home to tanker, reconnaissance and special operations aircraft over the next several years, it said.

The Pentagon also has selected RAF Lakenheath in the UK to be the first permanent European base for the F-35 Joint Strike Fighter. The first aircraft are scheduled to arrive in the UK in 2020 to replace F-15 fighter jets, it said. "The decision reflects the closeness of the US-UK defense relationship and the military value of the basing in the UK," added said.

The reduction in RAF Mildenhall would be partially offset as about 1,200 US military personnel would be permanently stationed at RAF Lakenheath along with two squadrons of F-35 fighters, the Pentagon said, adding that the net loss of US troops in Britain would be about 2,000.