(The Center Square) – The number of terror suspects captured trying to enter the U.S. illegally has soared since President Joe Biden took office.

But with more than 1 million unidentified foreign nationals evading apprehension after entering the U.S., the potential that at least some are on the international terrorist watch list poses a potential major threat to national security and raises the chances of terror attacks, observers warn.

Federal data shows 525 known or suspected terrorists were apprehended by agents at the northern and southern borders as they tried to illegally enter the country through the first nine months of this fiscal year. That is up from 478 all of last fiscal year.

The elevated figure does not include the terror suspects who illegally entered the country and evaded arrest, what U.S. Custom and Border Protection calls “gotaways.” According to CBP agents who spoke exclusively to The Center Square, there have been 1.7 million “gotaways” since the beginning of 2021, when Biden took office, at least some of whom could have been on the terror suspect list. CBP doesn’t release gotaway data publicly.

“Our open borders and easily abused asylum policies are not just a magnet for millions of economic migrants, they are also an open invitation for people who are intent on doing harm to our nation,” Ira Mehlman of the Federation for American Immigration Reform told The Center Square. “International terrorist organizations and criminal cartels are very aware of our vulnerabilities and will not hesitate to exploit them.”

The Department of Homeland Security did not respond to a request from The Center Square for comment.

Lora Ries, former acting deputy chief of staff at the Department of Homeland Security, told The Center Square that the current state of the border is a major national security threat.

“Remember, the 9/11 terrorist attacks were carried out by just 19 people,” said Ries, who now works as an analyst at the Heritage Foundation. “As this administration lets millions of unknown and potentially dangerous aliens into the country with no oversight, the question of the next attack on American soil becomes less of an ‘if’ and almost certainly ‘when?’”

An overwhelmed border was on full display in a recent government watchdog report. A DHS Office of Inspector General report released in June showed that border patrol agents caught and released a migrant into the U.S. even though the migrant was on the terror watch list.

The report points out that because of miscommunication and problems sharing information within the government, it took U.S. Immigration and Customs Enforcement weeks to arrest the terror suspect in the U.S., more than enough time to execute an attack.

“This occurred because CBP’s ineffective practices and processes for resolving inconclusive matches with the Terrorist Watchlist led to multiple mistakes,” the report said. “For example, CBP sent a request to interview the migrant to the wrong email address, obtained information requested by the [FBI Terrorism Screening Center] but never shared it, and released the migrant before fully coordinating with the TSC.”

With incidents like this and the continued flood of illegal immigration, experts say the nation is at risk because of the chaos at the southern border.

“But what is more worrisome is how many people on the terror watch list might be among the 1.5 million known gotaways who have entered under President Biden’s watch,” said Mehlman, who formerly worked for the U.S. House Defense Appropriations Subcommittee. “Border Patrol agents will tell you that while they have been tied up processing economic migrants making fraudulent asylum claims, the cartels have been taking advantage of the situation to bring in contraband and people who are coming for other reasons.”

While media focus on terrorism has declined since the attacks in 2001 and ensuing overseas conflicts, the FBI still considers it a top threat. In a speech for students at Texas A&M University earlier this year, FBI Director Christopher Wray said “the terrorism threat today is as persistent and complex as ever.” He also noted the “serious threats coming across our Southwest border,” which includes cartel activity and fentanyl.

Mehlman argues border agents do not have the resources to vet the flood of illegal migrants captured at the border.

“Given the volume of people entering the country – more than 7 million people have entered the U.S. illegally under this administration – the border enforcement agencies do not have the time or resources to thoroughly vet people before they are released,” he said.

Ries told The Center Square that many of the migrants are also from rivals of the U.S., like China, also opening the door to further spying.

“Some of those ‘gotaways’ are undoubtedly from adversarial countries, like China,” Ries said. “The number of Chinese nationals encountered at the border has more than doubled since 2020. Meanwhile, the CCP has tried repeatedly to spy on Americans and a Chinese-owned lab was discovered in California harboring dangerous bioweapons.”