Lawmakers have reached an agreement on a $633 billion defense authorization bill for fiscal 2013 that includes major changes to the nation’s export control system and adopts a compromise on U.S. Air Force structure changes.

The conference version of the bill, scheduled to be voted on by the House Dec. 20, also allows Pentagon biofuels investments to continue and asks the Defense Department to “evaluate” three sites for an additional national missile defense system.

But the final version of the bill does not require the Pentagon to put forward an operational deployment plan as the House bill had sought.

The Senate is slated to vote on the bill Dec. 20 or 21, and it is expected to pass by the end of the week.

One of the most contentious fights this year took place between Congress and the Pentagon over the Air Force’s proposed reductions to its force structure, the brunt of which fell on the Air National Guard. The initial drafts of the House and Senate bills proposed pausing any aircraft retirements or transfers.

But that changed after Defense Secretary Leon Panetta came back with a counterproposal in November that rolled back the proposed aircraft retirements and personnel reductions. Lawmakers are accepting that compromise, but continuing to require the Air Force to maintain another 32 C-130 or C-27J tactical airlift aircraft to meet Army airlift requirements.

Compared to the Air Force’s original fiscal 2013 plan, the conference report requires the service to restore 106 aircraft and about 5,400 personnel to the Air National Guard and the Air Force Reserve. That is more than 50% of the aircraft and 73% of the personnel originally proposed for elimination from the guard and reserve. The Air Force will then be allowed to continue with other retirements and transfers. But going forward, the bill would establish a commission to review future force structure changes.

The conference report also continues the prohibition on retiring Global Hawk Block 30 aircraft in fiscal 2013.