President Biden authorized Thursday to send 1,500 active-duty soldiers to the U.S.-Mexico border for 90 days to help U.S. Customs and Border Protection combat international drug trafficking.

About 2,500 National Guard members on active duty orders are already stationed in all nine sectors of the southwestern border doing detention and surveillance duties at CBP, a US official said Monday.

The new increase brings the total to 4,000 military personnel

US

border. the

US

official said the 1,500 soldiers will fill criticism

“

capacity shortfalls,” such as ground-based detention and monitoring, data entry, and warehouse support, until CBP can replace them with contractors.

The service members, who were requested by the Department of Homeland Security, will not do so

to carry out

any law enforcement work, the official said.

Biden signed the executive order “under authority to order the Armed Forces Ready Reserve to active duty to deal with international drug trafficking” on Thursday. The order promotes a

not from

December 2021,

order

who declared one

national

state of emergency to address the national security threats of drug trafficking.

The move comes ahead of the expected end of Title 42 orders on May 11, which were executed amid the COVID-19 pandemic and prevented migrants from seeking asylum, prompting border agents

fast

many of them back

fast

back to Mexico. The agency expects an increase in the number of migrants attempting to enter the US

San Diego Union-Tribune staff writer Kate Morrissey contributed to this report.