The Air Force is outlining its plan to reduce personnel and retire or transfer air fleets in the coming years as part of a massive overhaul.

In all, 3,900 active duty, 5,100 Air Guard, and 900 Air Force Reserves will be cut in the next year. The structure changes are detailed in a report that says the changing geopolitical environment and fiscal responsibilities warranted a reassessment of the nation's defense strategy.

In San Antonio, the C-5A fleet at Lackland Air Force Base will start its retirement process next year. It is set to be completed by 2016, when eight C5Ms will be transferred from Westover Air Force Reserves base in Massachusetts to Lackland to replace the C-5As.

The Air Force expects to save $8.7 billion by retiring hundreds of aircraft that affects 60 installations and 33 states.

President Barack Obama laid out the new defense strategy during his third State of the Union address. He says the proposal will save nearly half a trillion dollars in the U.S. budget.

Critics say cuts will trickle down to a greater demand on a force that's projected to take massive hits in the coming years. Retired Major Gen. Gus Hargett, Jr. says the plan "reduces the Air Force's ability to quickly respond to unforeseen contingencies in the future."

Air Force leaders say the transition will take the service from an emphasis on today's wars to preparing for future challenges while still focusing on countering terrorism and homeland security.