The Senate Appropriations Committee (SAC) on Nov. 21 unveiled a nearly $651 billion fiscal year 2018 defense appropriations bill that adds $15.4 billion to the Trump administration’s budget request to boost such areas as aircraft procurement, missile defense, readiness and shipbuilding.

The release of the chairman’s mark paves the way for negotiations with the House, which passed a $658.1-billion version of the defense bill in July. But committee leaders cautioned that the bill’s funding will automatically be slashed by tens of billions of dollars if Congress does not reach a budget agreement by Jan. 15 to prevent the return of budget caps mandated by the Budget Control Act of 2011.

“This proposal recommends funding for programs necessary to protect U.S. national security interests,” said Sen. Thad Cochran (R-Miss.), the committee’s chairman. “However, we still require a budget agreement to establish a top-line funding level for national defense spending. I am optimistic we will be able to write a final bill that supports a strong U.S. force structure and makes needed investments in readiness, shipbuilding programs, aircraft procurement, and missile defense.”

Sen. Patrick Leahy (D-Vt.), the SAC’s ranking member, and Sen. Dick Durbin (D-Ill.), the ranking member of the SAC’s defense panel, said the budget agreement should contain “equal investments” in military and non-military spending. Republicans have resisted such parity, saying defense spending is a higher priority.

In aircraft procurement, the SAC bill adds $1 billion for eight F-35Bs and F-35Cs for the Marine Corps and Navy, and $120 million for Air Force F-35A advance procurement to increase FY 2019 planned purchases.

The bill also adds $800 million for eight MC-130J special operations aircraft, $739 million for 10 Navy F/A-18E/F Super Hornets, $495 million for six Marine Corps and Navy V-22 tilt-rotor aircraft, $400 million for eight Navy MH-60R helicopters, $343 million for four Marine Corps KC-130J tankers and $309 million for nine Army AH-64E Apache helicopters.

The bill also contains $9.3 billion for missile defense, $1.4 billion above the request; $21.8 billion for Navy shipbuilding, $1.4 billion above the request; and $15.1 billion for munitions, $731 million above the request. To improve aviation readiness, the Air Force, Marine Corps and Navy would receive an additional $750 million for repair parts.