Biden administration official under investigation for withholding information on terror watchlist migrants.

The Biden administration is being questioned by Congress over its refusal to reveal the nationalities of individuals on the FBI terror watchlist who were arrested by Border Patrol.

"Sen. Tom Cotton, R-Ark., believes that the reason for withholding information about terror suspects' nationalities is not privacy or security concerns, but rather political reasons that would alarm the American people," Mayorkas wrote in a response to Cotton's letter. "Once again, you're attempting to conceal evidence of the Biden-Harris administration's border crisis."

Last week, the Customs and Border Protection (CBP) reiterated its denial to Planet Chronicle' request for the nationalities of suspects on the FBI terror watchlist who were arrested at the southern border by Border Patrol.

The Terrorist Screening Dataset, previously known as the watchlist, encompasses both known and suspected terrorists, as well as individuals who may pose a potential threat to the U.S., including affiliates of those on the list.

The request for only nationalities of those encountered was denied, citing privacy and security concerns. Fox made the request in October last year and was initially denied in May. The agency reiterated its reasoning last week.

"The Customs and Border Protection (CBP) agency stated in a letter to Fox that it is dedicated to safeguarding the privacy of individuals and preventing the disclosure of any personal information, either directly or indirectly. Revealing data for a specific nationality or group of individuals could potentially lead to identification, particularly by organizations that are familiar with the individuals in question."

The agency asserted that disclosing the information would expose the methods employed in capturing terrorists during the investigation process.

The provision of this information could enable targets to modify their actions to evade detection and exploit the weaknesses in CBP's law enforcement intelligence, while also compromising national security. Furthermore, providing the requested information could reveal terrorist travel patterns by region, which could alert terrorists about the government's knowledge of their travel plans, enabling them to take countermeasures against investigators and their investigations.

The agency contended that revealing nationalities could enable malicious actors to evade CBP's law enforcement operations and exploit any weaknesses in CBP's enforcement strategies.

Cotton, however, was not convinced by the reasoning provided.

"If the Biden-Harris administration impartially enforced our laws and deported illegal aliens regardless of their origin, terrorists wouldn't be able to game the system in the manner you describe."

He later states that "the American public has a right to be informed about who is entering our country, particularly when those unauthorized immigrants have links to terrorism."

"I can't believe I have to write that sentence," he said, "because contrary to your bizarre assertion, the security measures taken against illegal aliens suspected of terrorism far outweigh their privacy rights."

The letter requests the information by Sept. 10.

More than 560 nationals on the terror watchlist were encountered at the ports of entry last fiscal year, while 172 such encounters occurred at the border between ports of entry.

Planet Chronicle' Bill Melugin contributed to this report.