The Trump administration plans to take more than $1 billion from the National Guard and use it to fund border security, including new fencing, according to two congressional sources briefed on the matter.

In total, the Pentagon aims to move $3.8 billion from their annual budget to border security spending, one of the sources said. Of that, about $1.3 billion will come from the National Guard and reserves equipment budget and will instead be spent on bollard-style fences, roads, and sensor lights in areas on federal land, according to the sources. The Trump administration cites cross-border drug trafficking as justification for the spending.

In a letter to acting Homeland Security Secretary Chad Wolf reviewed by The Daily Beast, Defense Secretary Mark Esper wrote that the money would support “efforts to secure the southern border by blocking up to 13 drug-smuggling corridors along the southern border through the construction of roads and fences and the installation of lighting.”

In a statement, Wolf said the Pentagon “continues to be a steadfast partner in our border security mission… the DOD funding will help us build 177 additional miles [of new border wall system] and secure the homeland.”

According to a Department of Defense spokesperson, the Pentagon “used its statutory authority to provide support that aids in blocking drug-smuggling corridors across international boundaries of the United States.”

“Last month we received a new request from the Department of Homeland Security asking for assistance in blocking drug-smuggling corridors on federal land along the southern border of the United States,” the spokesperson said. “In response, the Secretary of Defense authorized support of $3.8B to build approximately 177 miles of fencing that will help to protect our borders.”

Congressional Democrats moved quickly to condemn the move on Thursday.

“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,” said House Appropriations Chair Nita Lowey (D-NY) and Rep. Pete Visclosky (D-IN) in a statement.

“Congress rejected President Trump’s full request for wall funding,” said the lawmakers, “which is why he is now orchestrating this backdoor mechanism to prop up a political vanity project.”

Sen. Jeanne Shaheen (D-NH), a top lawmaker on the Senate Armed Services and Appropriations panels, blasted the decision, saying, “These weapons and equipment are fundamental to military readiness.”

“The President needs to stop treating funding for our national security as a slush fund for his wall,” she added.

Members of the Senate GOP, which has typically opposed the administration’s direction of other funds to the wall, also met this latest move with a chilly reception.

When Sen. Lisa Murkowski (R-AK) saw the news break on Thursday, she grimaced.

“I can tell you every bit of equipment, every asset that we have for our Guard is important, essential, and I know the need,” she told reporters. “Once again you have the executive moving across the lines of authority there. And I don't think that that's right. I don’t think it should be allowed.”

Defense One first reported the change.