EAGLE PASS, Texas (NewsNation) — The Biden administration has instructed Texas to stop impeding the Border Patrol’s access to a park along the Rio Grande after the state National Guard took over last week.

“Texas’s actions are clearly unconstitutional and are actively disrupting the federal government’s operations. We demand that Texas cease and desist its efforts to block Border Patrol’s access in and around the Shelby Park area and remove all barriers to access in the Shelby Park area,” Department of Homeland Security General Counsel Jonathan Meyer said in a letter to Texas Attorney General Ken Paxton.

Paxton responded to Meyer Wednesday, slamming Biden for authorizing DHS to “send a threatening letter through its lawyers” instead of “addressing Texas’ urgent requests for protection.”

“But Texas has lawyers, too, and I will continue to stand up for this State’s constitutional powers of self-defense,” Paxton wrote in a letter of his own. “Instead of running to the U.S. Department of Justice in hopes of winning an injunction, you should advise your clients at DHS to do their job and follow the law.”

Texas Gov. Greg Abbott ordered the Texas Military Department to assume control of Shelby Park in Eagle Pass on Jan. 10, preventing Border Patrol access to about 2 1/2 miles of the U.S.-Mexico border.

Homeland Security has instructed the state to stop its operations and allow agents entry. Failure to comply could lead DHS to refer the matter to the U.S. Department of Justice on Wednesday.

Despite the Biden administration’s warning, Texas officials told NewsNation that military operations at Shelby Park will continue. On Wednesday, Texas’ Department of Public Safety confirmed to NewsNation’s Ali Bradley that they will not be allowing Border Patrol into the area.

NewsNation gained access inside Shelby Park, revealing two command centers and the construction of new fencing by the Texas Military Department.

NewsNation cameras captured a migrant attempting to cross concertina wire, blocked by National Guard members using riot shields. Texas officials said their goal is to halt another migrant surge, citing more than 71,000 migrant encounters in the area last month.

“The whole idea behind this whole taking over Shelby Park was to prevent another processing center to be set up under the bridge,” said Texas Department of Public Safety Lt. Chris Olivarez. “We saw what took place in December. That just continued to attract more illegal immigrants to cross the river, because they knew that if they could get to a certain point, which was Shelby Park, they would be processed.”

However, White House press secretary Karine Jean-Pierre said blocking the Border Patrol takes away from the agency’s duties.

“(Abbott’s) not really interested in solutions, only seeking to politicize the border,” she said.

DHS says that on Jan. 12, agents were “physically barred” from entering Shelby Park by Texas National Guard members to help three drowning migrants. However, according to a new DOJ filing, Mexican officials told border agents that three migrants had already drowned by the time they received a distress call.

NewsNation has confirmed Mexican officials performed the recovery operation.