The US government will delay procurement of Lockheed Martin F-35Cs by two years and ground its aging fleets of Fairchild Republic A-10s, Lockheed U-2s and Bell OH-58D Kiowa Warriors under the US Department of Defense’ fiscal year 2015 budget proposal.

The changes, which must be approved by the US Congress, were announced by US Secretary of Defense Chuck Hagel during a 24 February press conference.

The drawdowns and delays, a response to US budget cuts, are part of a broad plan outlined by the Pentagon today to shrink the size of the US military.

Hagel says the U-2’s high-altitude reconnaissance role will be fulfilled by Northrop Grumman’s RQ-4 Global Hawk unmanned air vehicles, and USAF officials have said the A-10’s close-air support role can be assumed by USAF F-35As and other aircraft.

Hagel also says he approved a plan to transfer the National Guard’s Boeing AH-64 Apache helicopters to the army in exchange for the army’s Sikorsky UH-60 Black Hawks.

The Pentagon intends to slow F-35 Joint Strike Fighter procurement overall by 24 aircraft through fiscal year 2019, Hagel says.

Otherwise, however, the Joint Strike Fighter programme would remain largely unscathed under the Pentagon’s plan.

Hagel says the changes will “allow the military to protect our country” but create “increased levels of risk” in the near term.

“The military will continue to experience gaps in training and maintenance, putting stress on the force and [affecting] our ability [to ensure] global readiness.”

Specific details are expected to be released on 4 March when President Obama releases his budget proposal.

The budget must then be approved by the US Congress, which often is hesitant to approve aircraft retirements.