Two key House lawmakers on Wednesday slammed a Pentagon proposal that would limit what top brass tells Congress about operational plans and orders.

The internal proposal, mandated by Acting Defense Secretary Shanahan, was recently sent to lawmakers in the House and Senate. The Washington Post was first to report the news.

In the memo, Shanahan, who was recently nominated by President Donald Trump to take the position permanently, highlighted new guidelines that would require military officials to evaluate whether the Pentagon should provide detailed military plans to lawmakers or a "summary briefing" of a plan instead, the Post said.

Following the report, House Armed Services Committee Chairman Rep. Adam Smith, D-Washington, and ranking member Rep. Mac Thornberry, R-Texas, said the guidelines single out lawmakers as a "security risk" rather than their role as the additional oversight needed for Pentagon operations.

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"This policy … accuses Congress of being a security risk for classified information, which is both inexcusable and inaccurate," Smith and Thornberry said in a joint statement Wednesday. "The department is not in a position to evaluate defense committees' worthiness to receive classified information, nor characterize our ability to appropriately protect it."

They continued, "If implemented, the department's new policy guidance would dramatically limit Congress' ability to execute our constitutional prerogative. The department is overstepping its authority by presuming to determine what warrants legislative oversight."

Thornberry and Smith added that this issue will be addressed in the National Defense Authorization Act, but did not specify whether it would be in the current fiscal 2020 request that lawmakers are in the process of finalizing.

In March, House lawmakers balked at another unpopular move by Shanahan: The Pentagon notified Congress it would reprogram up to $1 billion of infrastructure funding on the U.S. southern border in response to a request from the Department of Homeland Security. Though the House Armed Services Committee did not approve the reallocation of funding, the Pentagon was still able move forward on the effort because it did not break any legal requirements.

Since former Defense Secretary Jim Mattis' departure-turned-ouster in December, Shanahan, a former Boeing executive recently cleared in an ethics probe of showing favoritism to his former employer, has juggled issues ranging from the Pentagon's role at the U.S.-Mexico border to the latest show-of-force operations the U.S. is conducting as a message to Iran. As a result, lawmakers in recent months have voiced their concerns about the Pentagon's global footprint.

The proposal to limit information sharing with Congress could complicate matters for Shanahan, who is expected to go before the Senate next month to begin his confirmation process.

"By applying this policy to all members of Congress, regardless of committee assignment, the department misunderstands the role and prerogatives of its committees of jurisdiction," Smith and Thornberry said.

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @Oriana0214.