The Pentagon sent a notice to Congress Thursday afternoon announcing plans to repurpose $3.8 billion in order to fund the construction of a wall along the U.S.-Mexico border wall.

What are the details?

The Department of Defense money was originally intended to pay for "new aircraft, naval ships, and equipment for the National Guard," the Wall Street Journal reported.

In its report on the news, The Hill noted that the money is being repurposed as part of the Pentagon's counter-drug fund. According to The Hill, the notice says that the money is going toward the "support of higher priority items" and is "required to provide support for counter-drug activities."

"DHS has identified areas along the southern border of the United States that are being used by individuals, groups, and transnational criminal organizations as drug smuggling corridors, and determined that the construction of additional physical barriers and roads in the vicinity of the United States border is necessary in order to impede and deny drug smuggling activities," the notice says.

Last year, President Donald Trump declared the crisis at the southern border a national emergency. The declaration freed Trump to transfer military funds to pay for the border wall after Congress rejected appropriating the funding he requested.

Opponents of the declaration in Congress have repeatedly attempted to undo it but have thus far failed to block the president's vetoes.

Some in Congress are raging

In response to the news, several congressional members on Capitol Hill are decrying the move as unconstitutional and dangerous.

"President Trump is once again disrespecting the separation of powers and endangering our security by raiding military resources to pay for his wasteful border wall," House Appropriations Committee Chairwoman Nita Lowey (D-N.Y.) said in a joint statement with Defense Appropriations Subcommittee Chairman Pete Visclosky (D-Ind.).

"The President has stolen from the men and women of our military, their families, and the American taxpayers all to pay for a failed campaign promise and endanger our national security," Sen. Patrick Leahy (D-Vt.), the Senate Appropriations Committee vice chairman, said.

On the Republican side, the ranking member on the House Armed Services Committee, Rep. Mac Thornberry (R-Texas), also expressed concern over the move and called on Congress to "take action."

According to The Hill, Senate Appropriations Committee Chairman Richard Shelby (R-Ala.) also expressed regret over the move, despite his support for border wall construction.

"I like the wall, I support the president, I wish they'd find the money somewhere else," Shelby said. "I wish we could fund it through the regular process."