The Defense Department's budget for next fiscal year requests $4 million to begin planning a round of base closures to begin in 2019 - and the department is threatening unilateral action if Congress once again denies the request.

The department for several years now has asked Congress to authorize another round of Base Realignment and Closure but has been blocked by lawmakers worried that military installations in their states and congressional districts could be on the chopping block.

"The need to reduce excess facilities is so critical that, in the absence of authorization of a new round of BRAC, the administration will pursue new options to reduce wasteful spending on surplus infrastructure within existing authorities," the White House Office of Management and Budget says in its fiscal 2017 budget blueprint.

This fiscal year, Congress opened the door to a future BRAC round, allowing the Pentagon to begin studying its excess infrastructure after years of prohibiting even that. The military is conducting that analysis now.

As they make a new case for BRAC, Pentagon leaders are expected to tell Congress that previous rounds of base closures are now saving the department $12.5 billion a year.

A new BRAC round, according to the White House, "is critically important to re-align resources currently consumed by maintaining unneeded facilities."