"The Chinese Communist Party (CCP) has already proven they will stop at nothing to infiltrate the United States, and that threat is increasing every day as Chinese nationals use a visa loophole to gain access to our critical military installations in Guam," Ernst told Newsweek on Monday.

"Instead of listening to my calls to close this gap and prevent further CCP espionage, the Biden administration dragged their feet for four months and now is defending an outdated policy," she said.

"Make no mistake, they are putting our military secrets at risk. We must change this visa policy and put an end to Chinese nationals accessing our military installations on U.S. territories for any malign activity," Ernst said.

On April 1, DHS responded to lawmakers by saying the codified policy requires DHS to identify countries from which the CNMI receives a "significant economic benefit" from the number of visitors for pleasure within the year preceding enactment.

The DHS determined that the People's Republic of China (PRC) met this economic threshold in 2009.

"DHS responds to congressional correspondence directly via official channels, and the department will continue to respond appropriately to congressional oversight," a DHS spokesperson told on Tuesday.

According to the CNRA, as of October 3, 2019, PRC nationals can travel to the CNMI without a visa for a temporary visit for business or pleasure for up to 14 days. That authorization does not include employment.

Individuals without a visa are not authorized to travel to other parts of the United States, including Guam. When such individuals are encountered at CNMI airports, Customs and Border Protection officers are instructed to prohibit their travel to other U.S. destinations.

The CNMI is about 120 miles north of Guam, a U.S. territory, and 1,500 miles east of the Philippines, just over three hours from Tokyo by plane.

"DHS remains vigilant in its screening and vetting duties, which focus on rooting out exploitation of our immigrant and nonimmigrant visa processes, including by identifying, and where necessary denying entry to, high-risk travelers," the department wrote in its correspondence.