The Pentagon will consolidate forces in Europe, taking thousands of U.S. military and civilian personnel out of bases mostly in the U.K. and Portugal.

The changes will save about $500 million each year. The restructuring takes U.S. troops out of about 15 bases and will happen over several years.

The U.S. also has chosen RAF Lakenheath in Britain to be the first permanent European base for the F-35 Joint Strike Fighter. The first F-35 aircraft would arrive in the U.K. in 2020 to replace F-15 fighter jets.

The Pentagon says the changes involve the Army and Air Force and would result in the overall reduction of about 2,000 U.S. personnel in the U.K.