EXCLUSIVE: Former President Trump said the Biden administration is only citing the “immediate need” to build a border wall because President Biden is watching the United States be “invaded” by illegal migrants, warning that “terrorists” are “already” inside the country.

Department of Homeland Security Secretary Alejandro Mayorkas on Wednesday said there was an “acute and immediate need” to waive dozens of federal laws in order to build a border wall in south Texas where illegal migration has surged. DHS justified the move due to “high illegal entry” — more than 245,000 migrant encounters have been recorded in the Rio Grande Valley Sector this year.

In an exclusive interview with Fox News Digital shortly after the DHS announcement, the former president — who leads the 2024 Republican primary field by a massive margin — blamed Biden for halting construction of the border wall and causing the crisis at the southern border.

“Biden sees our country is being invaded,” Trump said. “What is he going to do about the 15 million people from prisons, from mental institutions, insane asylums, and terrorists that have already come into our country?”

The number of people arrested in FY 2023 between ports of entry by Border Patrol at the southern border who are on the FBI’s terror watchlist hit a new record this year, with 151 arrests in FY 23, compared to 98 in FY 2022 and 15 in FY 21. At the ports of entry at the northern and southern border, there have been 505 people encountered by Customs and Border Protection’s Office of Field Operations.

The watch list, officially called the Terrorist Screening Dataset (TSDS) is the government’s database that “contains sensitive information on terrorist identities.” The watch list originated to house information on known or suspected terrorists, but “has evolved over the last decade to include additional individuals who represent a potential threat to the United States, including known affiliates of watchlisted individuals,” CBP says.

While the number is relatively small, compared to the millions of migrants encountered at the borders in recent years, Republicans and former border officials have raised concern about the numbers of those on the terror watch list who are getting past Border Patrol agents. There were at least 599,000 illegal immigrants who escaped Border Patrol custody in FY 2022, after more than 390,000 in FY 2021.

“What has happened to our country?” Trump said, adding that the Biden administration needs to “go back to Trump policies.”

“He has to reinstate Remain in Mexico and Title 42,” Trump said. “He has to do all of the other things that we were doing.”

A Trump campaign spokesperson told Fox News Digital Wednesday night that “President Trump is always right.”

“That’s why he built close to 500 miles of powerful new wall on the border and it would have been finished by now,” the spokesperson said. “Instead, Crooked Joe Biden turned our country into one giant sanctuary for dangerous criminal aliens.”

The comments come after Department of Homeland Security posted an announcement Wednesday night on the U.S. Federal Register which outlines construction in Starr County in the Rio Grande Valley Sector.

Mayorkas says he is using his authority provided by Congress to waive 26 federal laws, including the Clean Air Act, Safe Drinking Water Act and Endangered Species Act.

“There is presently an acute and immediate need to construct physical barriers and roads in the vicinity of the border of the United States in order to prevent unlawful entries into the United States in the project areas pursuant to sections 102(a) and 102(b) of [the Illegal Immigration Reform and Immigrant Responsibility Act of 1996],” Mayorkas said.

A Customs and Border Protection spokesperson told Fox News Digital Wednesday that the project is “consistent with DHS’s plan to fulfill the requirements of President Biden’s Proclamation, which ended the diversion of funds for border wall from military projects or other sources while calling for the expenditure of any funds Congress appropriated for barrier construction consistent with their appropriated purpose.”

The construction is funded by the FY 2019 DHS appropriations bill, which specifically funded wall projects in the RGV Sector and which DHS is required to use for its appropriated purpose. Customs and Border Protection (CBP) announced plans for up to 20 miles of wall in the RGV Sector in June. The administration previously made moves to close gaps and replace gates, and says that such projects prioritize the completion of activities and projects to address life, safety and operational risks — including the safety of individuals, Border Patrol agents and migrants.

A CBP spokesperson confirmed to Fox News Digital that the waiver is for barrier projects announced in June, and that it will cover approximately 17 miles in Starr County. The spokesperson said that the project is consistent with DHS’ plan to fulfill President Biden’s Jan 20, 2021 proclamation which “ended the diversion of funds for border wall from military projects or other sources while calling for the expenditure of any funds Congress appropriated for barrier construction consistent with their appropriated purpose.”

“CBP remains committed to protecting the nation’s cultural and natural resources and will implement sound environmental practices as part of the project covered by this waiver,” the spokesperson said.

The administration had put a halt to new border wall construction in early 2021, after then-candidate Biden had promised there would “not be another foot of wall constructed on my administration.” The administration said that wall construction under the Trump administration was “just one example of the prior Administration’s misplaced priorities and failure to manage migration in a safe, orderly, and humane way.”

The announcement comes as the Biden administration is facing a fresh surge in illegal immigration, leading to record-high numbers at the southern border and intense political criticism from both Republicans and Democrats. Customs and Border Protection (CBP) sources told Fox News last week that there were more than 260,000 encounters in September — which would be the highest monthly total on record.

Meanwhile, Trump last month vowed, if re-elected, to carry out “the largest domestic deportation operation in American history,” and promised to begin a second term by “immediately” terminating “every Open Borders policy of the Biden Administration.”