(NewsNation) — House Republicans are demanding the Department of Homeland Security explain how multiple terror suspects were allowed into the U.S.

In a letter to DHS Secretary Alejandro Mayorkas, exclusively obtained by NewsNation, House Homeland Security Committee Chair Mark Green, R-Tenn., and two other House Republicans specifically name four suspected terrorists who entered the U.S. and were identified after already being in the country.

All four have been arrested, but they spent a significant amount of time in the U.S., one of them a full year, before being taken into custody by law enforcement.

In a statement, Green said the incidents are an example of Mayorkas’ “breach of the public trust” and referred to his impeachment, which narrowly passed in the House on a second vote.

“Secretary Mayorkas waited three years to admit there even is a border crisis, and during that time, at least 1.8 million illegal aliens evaded apprehension at the border. While we may never know the full extent of the homeland security crisis Secretary Mayorkas has unleashed, the apprehension of an alleged member of Hezbollah at the border just last month gives Americans a terrifying glimpse at the possibilities,” Green said. “This impeached DHS secretary has empowered America’s adversaries through his open-borders agenda, and he must be held accountable.”

The cases involve a member of al-Shabaab, a designated terror organization operating in Africa. The individual was caught while illegally crossing the southern border but released after being declared a “mismatch,” only to be located almost a year later after a “redetermination” was made.

A second case involved a Pakistani man allegedly on the terrorist watch list who was apprehended by Border Patrol a day after entering the U.S. but eventually released through the alternatives to detention program.

The remaining cases were that of a man arrested in North Carolina following a standoff with law enforcement, which led to authorities allegedly determining he was on the terror watch list, and an individual associated with Hezbollah who was detained near the border and allegedly stated he was going to make a bomb when questioned by authorities.

The lawmakers also reference “a stream” of people who are on the terror watch list who have entered or attempted to enter the U.S. across the southern border.

The letter gives the DHS until April 17, 2024, to turn over files on the individuals in question along with documents related to the decisions to release or arrest them.

DHS responded to NewsNation’s request for comment, saying the agency answers congressional inquiries through official channels and stating it is committed to working with law enforcement partners to identify individuals of concern.

“DHS and our intelligence, counterterrorism, and law enforcement partners screen and vet individuals prior to their entry to the United States to prevent anyone known to pose a threat from entering the country,” the statement read. “We do not disclose details about our vetting processes, however we continually evaluate procedures to ensure they remain relevant and effective in keeping the homeland safe and secure.”

A DHS official said vetting procedures used by Customs and Border Patrol include biometric and biographic screening for individuals encountered by authorities.

Read the full letter below: