Defense Budget and the Budget Control Act: Frequently Asked Questions [Updated September 30, 2019] [open pdf - 1MB]
From the Document: "Enacted on August 2, 2011, the Budget Control Act of 2011 as amended (P.L. 112-25, P.L. 112-240, P.L. 113-67, P.L. 114-74, P.L. 115-123, and P.L. 116-37) sets limits on defense and nondefense discretionary spending. As part of an agreement to increase the statutory limit on public debt, the BCA [Budget Control Act] aimed to reduce annual federal budget deficits by a total of at least $2.1 trillion from FY2012 through FY2021, with approximately half of the savings to come from defense. [...] Some defense policymakers and officials argue the BCA spending restrictions impede the Department of Defense's (DOD's) ability to adequately resource military personnel and equipment for operations and other national security requirements. Others argue the limits are necessary to curb rising deficits and debt."
CRS Report for Congress, R44039
Congressional Research Service: https://crsreports.congress.gov/