Defense Secretary Jim Mattis is urging Congress to reject a House proposal to set up a space corps in the Air Force Department, saying that the provision in the fiscal year 2018 defense authorization bill could harm the Defense Department’s ability to coordinate its space activities.

“At a time when we are trying to integrate the department’s joint warfighting functions, I do not wish to add a separate service that would likely present a narrower and even parochial approach to space operations vice an integrated one we’re constructing under our current approach,” Mattis wrote in a July 11 letter to Rep. Mike Turner (R-Ohio), who opposes the space corps proposal. “Because our Army, Navy, Air Force and Marines have their own equities in maintaining vital space operations, a properly integrated approach is better for carrying out this mission.”

Mattis also argued that the space corps proposal needs more study. He noted that his department is studying its space organization, as required by the FY 2017 defense authorization act, and plans to finish that review in September.

Air Force Secretary Heather Wilson expressed similar concerns in a separate letter to Turner, saying a space corps would create “additional seams between the services.” And in a statement of administration policy, the White House Office of Management and Budget called the space corps proposal “premature.”

Turner asked the House Rules Committee late July 12 to allow the full House to consider an amendment the week of July 9 to replace the space corps provision with language calling for a study on whether a new service is needed. Turner argued that most lawmakers have not examined the space corps proposal in depth and need more information, including hearings, before creating a new service.

“There’s been about 30 minutes of debate in the Armed Services Committee on this,” Turner said. “Certainly, I think it bears more.”

The House Armed Services Committee defeated a similar amendment during its consideration of the bill in late June. Rep. Mike Rogers (R-Ala.), chairman of the committee’s strategic forces panel, countered that his panel has thoroughly studied the space corps proposal and that the new service is urgently needed to streamline the Air Force’s excessive bureaucracy and make space a higher priority.