NO ONE is certain how President-elect Donald Trump intends to stiffen restrictions on immigrants and visitors to the United States, or what he means by “extreme vetting,” though there is little doubt he will try to tighten screening for many applying from Muslim countries.

What is clear is that beefed-up federal laws, rules, systems, programs and technology have added substantial layers of scrutiny for virtually every foreigner who has entered the country in recent years. Americans deserve to know that those entering the country have been screened carefully, but it will be difficult for Mr. Trump to fashion an even more muscular inspection and monitoring regimen without subjecting visitors and immigrants to outright religious profiling.

The advances in federal capabilities were highlighted last week when the Obama administration officially dismantled one post-Sept. 11 screening program, which seemed tough when it was enacted, because it had become obsolete. The program, known as the National Security Entry-Exit Registration System, was in use for nine years before being suspended in 2011, largely because other, newer systems had proved more effective at tracking and monitoring foreign travelers before and after they entered the country.

While it was in use, NSEERS entailed registering some 180,000 teenage boys and men from 25 countries, most of them Muslim — subjecting them to fingerprinting, interrogations and, in some cases, periodic visits from federal agents. At least 13,000 of them were placed into deportation proceedings after overstaying their visas or otherwise failing to comply with rules.

The program applied for the most part to law-abiding visitors and residents, and as far as is known, never produced any terrorist prosecutions. In 2012, the Department of Homeland Security’s inspector general, noting it had done little to enhance public safety while draining government resources, recommended that it be permanently dismantled. Now it has been, meaning the Trump administration would have to jump through additional hoops to resurrect it, or something like it.

Doing so may be a waste of effort. Since NSEERS was established, and even more since its demise, other programs have leapfrogged it. Automated systems now collect and store biographic and biometric data including digitized fingerprints, iris scans and facial data for most foreigners entering the country, including students. Foreign nationals from or those who have visited high-risk countries such as Syria, Iraq, Libya and Yemen are ineligible for participation in the U.S. visa waiver program, meaning they are subject to extra scrutiny when applying to come to the United States. Government databases are increasingly searchable and better at helping officials spot those who may pose threats to national security.

Those systems and programs, detailed by Homeland Security in explanation of NSEERS’s obsolescence, provide federal authorities with a range of tools to verify foreigners’ identities and monitor their movements. They apply broadly to visitors, travelers and immigrants. They also comport with constitutional standards and American values.

By contrast, a registry that singles out travelers from Muslim countries falls afoul of those standards — and may do little to enhance national security. While some prominent recent terrorist attacks in the United States and Europe were carried out by immigrants, the perpetrators of others, including the bloody assaults in Paris and Orlando, were by homegrown terrorists.