President Donald Trump’s administration has lately been ramping up scrutiny of all foreign nationals in the United States, rather than just focusing on undocumented immigrants. This has prompted concern among experts, including some former top officials in the U.S. Department of Homeland Security.The New York Times reported Friday on the aggressive approach the Trump administration has taken against noncitizens in recent weeks. A 35 year-old Canadian woman said she was placed “in chains” and detained for 12 days at the San Ysidro border crossing (one of the nation’s busiest). Two German tourists at that same border crossing were also detained and eventually deported after being kept in custody for multiple weeks.One French scientist who visited the U.S. earlier this month for a conference in the Houston, Texas area was subjected to so-called “enhanced vetting” procedures before eventually being turned away. Customs officials conducting “enhanced vetting” can demand access to a foreign visitor’s electronic devices to determine whether they can enter the country. In the case of the scientist, he was ultimately sent back to France after officials discovered he had “expressed a personal opinion” about the Trump administration’s scientific research policies.READ MORE: Trump Cabinet official doubts seniors would be upset over missed Social Security paymentsBut even those who lived in the U.S. for years and who have had no run-ins with authorities aren’t spared from harsh treatment by immigration authorities. Columbia University graduate student Mahmoud Khalil, who is a Syrian-born green card holder married to a U.S. citizen, was recently arrested and placed in deportation proceedings without even being charged with a crime. And Georgetown University postgraduate Dr. Badar Khan Suri was also recently arrested at his Virginia home by masked DHS agents and has been singled out for deportation. Both maintain that they were targeted for their pro-Palestinian activism.The administration has argued that legal residents like Khalil and Suri (who is an Indian national in the United States legally on a student visa) don’t need to be charged with a crime to be deported due to an obscure federal statute. That statute allows for the government to deport any noncitizen whose presence it believes could pose a threat to the administration’s foreign policy. But Will Creeley, who is the legal director for the Foundation for Individual Rights and Expression (which has filed an amicus brief in support of Khalil), told the Times that he believed the administration’s “clear motivation here is to chill speech.””Simply saying someone is aligned to a terrorist organization does not exempt them from First Amendment protections,” Creeley said. “The administration has not produced any evidence that Mr. Khalil’s expressive activity falls into the narrow or carefully defined exceptions to the First Amendment.”Gil Kerlikowske — who was once a commissioner for U.S. Customs and Border Protection and a police chief in four cities — noted that Trump’s hardline immigration policies are similar to those of his first time, but like “déjà vu all over again on steroids.”READ MORE: ‘Government abducting people’: Masked DHS agents take scholar into custody without charges”Whether it’s speech and criticism, green cards, they’re really taking it to a whole new level,” Kerlikowske told the Times.Additionally, former Homeland Security Secretary Janet Napolitano — who served during former President Barack Obama’s first term – insisted that Trump’s strict immigration measures were an attack on the Constitution. She also cast doubt on the administration’s reliance on the “foreign policy” statute cited in the cases of Khalil and Suri.”When the justification is ‘you’re a threat to national security’ and it’s like one individual, I mean come on,” Napolitano told the Times. “Let’s be real.”Click here to read the Times’ report in its entirety (subscription required). READ MORE: ‘This is not right!’ Elderly woman explodes at GOP senator over Social Security cuts