(TNND) -- President Donald Trump has refocused his crackdown on immigration in the wake of the shooting of two West Virginia National Guard soldiers, allegedly at the hands of an Afghan national.

Rahmanullah Lakanwal, 29, is suspected of shooting the soldiers who were deployed to Washington, D.C., as part of Trump's public safety campaign.

The exact motive for the attack remains unclear, but Homeland Security Secretary Kristi Noem told ABC News this weekend that Lakanwal might've been "radicalized" after coming to the U.S.

Lakanwal was admitted to the U.S. under the Biden administration as part of a program to resettle vulnerable Afghans who supported American forces during the war in Afghanistan.

And he was granted asylum by the Trump administration earlier this year.

Noem criticized the Biden administration for, in her view, not thoroughly vetting the Afghan refugees.

In the wake of the shooting -- which left Specialist Sarah Beckstrom, 20, dead and Staff Sgt. Andrew Wolfe, 24, wounded -- the U.S. Citizenship and Immigration Services halted all asylum decisions.

And USCIS Director Joseph Edlow said they've directed a full-scale, rigorous reexamination of every green card for every immigrant from every country of concern.

The administration also put a stop to visas for anyone holding an Afghan passport.

Trump told reporters Sunday aboard Air Force One that asylum decisions could be paused for "a long time."

"We don't want those people. We have enough problems. We don't want those people," Trump said.

Trump said he'd consider denaturalizing Americans, if he had the power, who were "criminals that came into our country and they were naturalized maybe through Biden or somebody that didn't know what they were doing."

Noem told ABC News that Trump is putting in place more rigorous vetting procedures for asylum applicants.

"If you don't know who they are, if they're coming from a country that's not stable and doesn't have a government that can help you vet them, that we shouldn't allow it," she said. "And that's why I'm so grateful that President Trump has taken the action that he's taken the last few days to stop all asylum, to stop all processes that bring people into this country until we ensure that we know who these people are."

Ernesto Sagás, an expert in politics and U.S. immigration policies who teaches at Colorado State University, said the shooting of the National Guard soldiers was tragic.

But he said Trump was also using the shooting as an excuse to clamp down even harder on immigration.

"This plays very well into Trump's perennial favorite issue, which is immigration," Sagás said. "Like, the solution to all of the problems in America, according to Trump, is to deal with people that shouldn't be here in this country. Is Trump overreacting? Usually, of course. He's always very bombastic, very over the top. But he seems to be refocusing his agenda on immigration after taking hits on the Epstein files and on the economy."

Shawn VanDiver, the president of AfghanEvac, which works to resettle eligible Afghan nationals who helped the U.S., said something similar in a Substack post Monday.

VanDiver condemned the shooting but said a whole group of Afghans shouldn't take the blame for one man's actions.

"This is collective punishment dressed up as national security," VanDiver wrote. "It is wrong on the facts, wrong on the law, and a betrayal of the promises this country made to its wartime allies. And, in reality, many of the changes in policy being enacted were already planned, but the Administration is using this tragedy as an excuse to roll out these severe and extreme restrictions."

Sagás disputed the notion that Lakanwal and other Afghan refugees weren't fully vetted.

"What is even more kind of disturbing, is this idea of going back and looking at cases of people that already have their green cards, and even people that have already been naturalized, and kind of re-vetting those cases that have already been decided," Sagás said.

He said that puts innocent people who immigrated legally at risk of getting kicked out of the country for minor infractions under the umbrella of national security concerns.

U.S. law allows a migrant to arrive at an American port of entry and apply for an asylum hearing so they can show they have a well-founded fear of persecution in their home country based on race, political opinion, membership in a particular social group, religion or nationality.

The immigration court asylum grant rate has been cut in half in the last year. Only about one in five asylum seekers were granted their request at last count.

But asylum, even if it's granted, is a temporary status, Sagás said.

Polling shows most Americans want violent criminals living in the country illegally to be deported.

But Sagás said Trump is "paring down to the bone" with his immigration crackdown. It may play well with his base, but Sagás said many Americans don't want to see green card holders or naturalized citizens deported.

At some point, immigration won't remain the same winning issue for Trump, Sagás said.

Cost-of-living concerns are most important to voters, he said.

"At some point, it's going to become less and less effective as they run out of the usual suspects or the usual targets," Sagás said.