Both Defense Secretary Ashton Carter and Joint Chiefs Chairman Gen. Dempsey testified in mid-March that the House defense budget, which uses emergency war funding to skirt defense spending limits, would be vetoed by the President if it passes through Congress.
The budget proposal, which would maintain the $523 billion cap for base spending and put $94 billion into the OCO fund, came from fiscal conservatives in the House Budget Committee. Other budgets have proposed exceeding the base budget cap and providing $577 billion for the base budget with $51 billion for the OCO fund.
DefSec Carter, in speaking to the House Armed Services Committee, made it clear that trying to use the money from the Overseas Contingency Operations (OCO) fund as a regular part of the budget "doesn't work, because to have the defense we need and the strategy we have laid out, we need the budget we have laid out not just this year, but for the years to come". Gen. Dempsey echoed Carter's concerns, saying "frankly [this budget] does not do for defense what we should be doing in a predictable fashion."
The primary problem with using the OCO fund as part of the regular budget involves the long-term planning that the Pentagon must do. Without a steady and predictable base budget many of the programs that the Pentagon is relying on in the future may be under-funded or lose funding entirely. These programs include not only the controversial ones (the F-35, for example), but also things like military housing, benefits, and other personnel costs.