Pentagon chief Patrick Shanahan on Monday endorsed the transfer of $1 billion to begin the construction of part of the U.S.-Mexico border wall that President Donald Trump has been seeking.

“Shanahan authorized the commander of the U.S. Army Corps of Engineers to begin planning and executing up to $1 billion in support to the Department of Homeland Security and Customs and Border Patrol,” a Pentagon statement affirmed.

“These funds will be used to support DHS's request to build 57 miles (92 kilometers) of 18-foot-high (5.5 meters) pedestrian fencing, constructing and improving roads, and installing lighting within the Yuma and El Paso Sectors of the border in support of the February 15 national emergency declaration on the southern border of the United States,” the statement elaborated.

The statement also explained that the Pentagon is allowed to make money transfers “to construct roads and fences and to install lighting to block drug-smuggling corridors across international boundaries of the United States in support of counter-narcotic activities of Federal law enforcement agencies.”

Democratic senators signed a petition opposing the act, as reported by CNN.

“We strongly object to both the substance of the funding transfer, and to the Department implementing the transfer without seeking the approval of the congressional defense committees and in violation of provisions in the defense appropriation itself. As a result, we have serious concerns that the Department has allowed political interference and pet projects to come ahead of many near-term, critical readiness issues facing our military,” the senators wrote.

The Trump administration is willing to use approximately $8 billion to construct fences along the U.S.-Mexico border, with $6.1 billion of that drawn from Pentagon accounts. A total of $2.5 billion is expected to be deducted from counter-drug programs and $3.6 billion from military construction funds.