Hasson’s arrest last week in Maryland, where he faces drug and gun charges, has raised questions about how the military screens for hate group affiliations or other threats, especially compared with how the Pentagon has approached vetting its foreign recruits — an arduous process that has led to a number of lawsuits.

Few tools to screen for hate group affiliation are available beyond visible tattoo inspections and a criminal record check during the enlistment and commission process, said Air Force Maj. Carla Gleason, a Pentagon spokeswoman. Individual military services have rules for how they rescreen and investigate potential violators after they are in uniform, she said.

By contrast, a Pentagon program for skilled foreign recruits designed to trade expedited citizenship for service requires layers of intensive vetting.

Recruits with valid visas are screened by the State and Homeland Security departments before even entering the program, and since 2016 they have been subjected to additional counterintelligence screening and security checks similar to a top-secret clearance.

Continuous vetting requirements, even after recruits had been naturalized, were reversed by a federal court after a judge ruled they were so stringent that they violated constitutional equal-protection laws. The Pentagon said it feared insider threats in the military.

“The military is neglecting checks on native-born Americans,” said Margaret Stock, a retired Army officer who helped implement the foreign recruit program at the Pentagon. “And they’re focused on vetting the least dangerous group in the military.”

The Pentagon could institute simpler broad checks for native-born and foreign recruits alike to block or catch more bad actors, she said.

The Defense Department said it feared security holes in the Military Accessions Vital to the National Interest recruitment program, or MAVNI, which was shuttered in 2017, though it acknowledged in court filings that none of the thousands of naturalized recruits from the program have been charged with espionage-related crimes.

One Chinese national who entered the program was charged with failing to report as a foreign agent but did not make it to basic training, and the new vetting procedures did not play a role in his detection, court filings said.

The additional Pentagon vetting became such a bureaucratic albatross that it essentially imploded the program. Other lawsuits and decisions related to vetting and naturalization procedures led to victories for immigrant recruits.

Similarly heightened screening for green-card holders has also been introduced and subsequently challenged.

Hasson, 49, was ordered held for 14 days as prosecutors weigh additional charges. He had previously served in the Marine Corps and the Army National Guard. Coast Guard officials said he is no longer in his position as an acquisitions officer at their Washington headquarters.

“Unlawful possession of drugs and firearms, as well as advocacy for supremacist doctrine, ideology, or causes, violates Coast Guard policy, the Uniform Code of Military Justice, and our organization core values,” said Lt. Cmdr. Scott McBride, a Coast Guard spokesman.

Hasson had held a secret security clearance since April 2005, McBride said, and he would have renewed it in 2015. It is unclear whether the clearance was revoked.

A Coast Guard member was reprimanded last month for flashing a hand signal associated with white supremacy on live TV.

White supremacists and neo-Nazis became an issue in the 1980s and ’90s, when officials ordered crackdowns to weed out individuals who sought access to weapons and tactical training to later use in a race war.

But white supremacists are still getting through. In 2017, an active-duty Marine took part in violence at the “Unite the Right” rally in Charlottesville, and two others hung a racist banner in North Carolina, prompting embarrassment in the service and a rush to emphasize that participation in such groups was not tolerated.

Existing measures are not adequate to combat extremism in the ranks, experts said.

“ 'Screening out’ ” isn’t a comprehensive enough answer for the threat posed by the white power movement,” said Kathleen Belew, author of “Bring the War Home: The White Power Movement and Paramilitary America” and a history professor at the University of Chicago. “What we need is a broad public conversation about this movement,” she said.

It is unclear how many service members with ties to hate groups are in the military. A 2017 poll by Military Times found a quarter of troops said they saw evidence of white nationalism in the ranks. The white power movement overall has taken cues from cell-style terrorism to make it harder for authorities to monitor and defeat, Belew said.

A lack of scrutiny for U.S. citizen recruits has recently led to other national security breaches.

In 2017, a dual French-U. S. citizen enlisted in the U.S. Army after he fought with Russian separatists in Ukraine and helped start an anti-Western militant group. He was assigned to an infantry unit in Hawaii undetected until a report by The Washington Post led to his discharge.

Dan Lamothe contributed to this report.