CNN — The Biden administration is making plans to send an additional 1,500 active-duty troops to the US-Mexico border in anticipation of an influx of migrants when the Title 42 public health authority expires next week, sources familiar with the planning told CNN.

The US military has long provided support to the Department of Homeland Security on the border and a surge of personnel to the area is not unprecedented. Currently there are approximately 2,500 National Guard troops on the border.

As they’ve done before, the troops would serve in administrative roles and not perform any law enforcement function, the sources said. Their assistance is intended to free up resources at the Department of Homeland Security so that US Customs and Border Protection can operate more freely in the field, the sources added.

“At the request of DHS, DOD will provide a temporary increase of an additional 1,500 military personnel, for 90 days, to supplement CBP efforts at the border. These 1,500 military personnel will fill critical capability gaps, such as ground-based detection and monitoring, data entry, and warehouse support, until CBP can address these needs through contracted support. They will not be doing any law enforcement work,” a US official said in a statement.

Last July, DHS Secretary Alejandro Mayorkas asked Defense Secretary Lloyd Austin for troops to help CBP starting October 1, 2022 through September 2023. Austin approved a deployment of 2,500 troops to the border, who remain there now, and the 1,500 troops are expected to join them in the coming days.

Former President Donald Trump’s administration approved similar troop surges to the border. In early 2019, over 3,000 additional active duty troops were deployed to the southern US border to bolster security, joining the 2,300 troops already there.

The expected migrant surge next week comes at a critical moment for Biden who on the heels of launching his 2024 bid, will also have to navigate another potential border crisis, opening him up to attacks from Republicans who have hammered the administration and are already wielding the issue to counter the president in the upcoming election and allies who argue his enforcement measures are too harsh.

“We do expect that encounters at our southern border will increase as smugglers are seeking to take advantage of this change and already are hard at work spreading disinformation that the border will be open after that. High encounters will place a strain on our entire system, including our dedicated and heroic workforce and our communities,” Mayorkas said Thursday.

“Let me be clear: Our border is not open and will not be open after May 11.”