Chin was right to raise such concerns. The U.S. is now engaged in a global battle for talent—and though it leads in the competition to attract the world’s top scientists and engineers, that lead has been slipping in recent years.

The Trump administration’s efforts to reform immigration surely won’t help. Combined with a rash of highly publicized hate crimes, like those against Indian engineers outside of Kansas City last month and a Sikh man near Seattle in early March—the ban rebrands the U.S. as an unwelcome mat that will likely dissuade skilled migrants from attending school or taking jobs in a country that is seen as insular, unpredictable, and untrustworthy.

But anyone who visits America’s great research universities can see that science and engineering are global enterprises. My research with doctoral student Natalie Novick reveals that computer science graduate programs in the U.S. typically have about 60% foreign-born students, and electrical engineering’s reliance on immigrants is even higher—upwards of 70% foreign-born studying in the U.S. Though China and India contribute the greatest number of students overall, at least one of the states on Trump’s list of dangerous states—Iran—is a major contributor of STEM students in the U.S. According to the Institute of International Education, Iranian students are more likely to study STEM fields than students in any other country.

Another area endangered by Trump administration migration policies relates to the financing of higher education. International students are now major contributors who help pay for higher education—and also contribute to local economies through their spending. This is especially true for America’s great public universities, which have seen drastic declines in state funding, so much so that tax revenues now constitute only about 10% of total support. Enrolling more international undergraduates is a way for state universities and colleges to make up for budget shortfalls, as these students usually pay full tuition.

American universities are participating in a global movement to attract both talented STEM students and international undergraduates in all degrees. And while the U.S. is increasing its overall undergraduate numbers, for several years it has been losing its overall share. For example, the U.S. hosted more than 800,000 international students in 2013, continuing an upward trajectory that had stalled for five years amid tighter U.S. visa restrictions following the Sept. 11 terrorist attacks. The next closest competitor was the U.K., at about 350,000. But between 2000 and 2012, the U.S. share of all international tertiary students fell from 23% to 16%. The U.K., Australia, and Canada all gained during that period, as did some other entrants to the competition—Russia, China, and South Korea.

Not surprisingly, the tech sector in general and Silicon Valley in particular are heavily dependent on STEM graduates, as well as temporary foreign workers on H-1B visas. Unlike outsourcing companies like Wipro, Infosys, and Tata, which use H-1B visas to train Indian workers to do American jobs and then move the jobs and workers back to India, large tech companies like Microsoft (MSFT), Google (GOOG), and Qualcomm (QCOM) frequently sponsor their H-1B workers for green cards—a clear indicator that the worker is considered valuable to the company.

While the U.S. remains the top destination for talented international students and STEM workers, other popular destinations are closing the gap. Talented people, especially those with software and engineering skills, have options. China and India, for example, have enticed growing numbers of graduates and workers from these countries to return home. Early indications already show that international students are looking beyond the U.S., and American enrollments may face a decline. The University of British Columbia in Vancouver reported that one graduate program received more than 30,000 hits between midnight and 3 a.m. on the night the U.S. elected Trump.

A new survey has found that almost one in three prospective international students has less interest in studying in the U.S. About 69% reported that the main reason was “concerns about the U.S. presidential administration,” while other major factors seemed linked to the political climate: concerns about travel restrictions, safety, and discrimination. The decline in interest was stronger among Muslim students, but the decline was seen across all nations. Another survey of more than 250 colleges and universities found that nearly 40% reported a decline in applications from international students. Major factors in the declines were concerns about visas and an unwelcoming climate.

There’s a saying that one super-talented developer is worth 20 average ones, and the super-talented have the most options. They seek opportunities, but they may be wary of unwelcoming environments. During the first dot-com boom, Germany sought to entice more Indian engineers to come, but a single, regional politician’s pithy line challenging the policy—Kinder statt Inder—or “(German) children instead of Indians”—created a public relations headache for Germany, and visas went unused. Increasingly, Trump’s order may make talented individuals wonder about America’s welcome mat, and ask: What executive order comes next? How much hassle will it be to travel to the U.S.? And with the president stoking foreigner resentment, will I have to fear for my safety?

A president who promised to “make America great again” may actually cause it to slip behind. National security theatre at our borders and in our visa policies does little to make us safe, and has consequences far beyond those directly affected.

John D. Skrentny is co-director of the Center for Comparative Immigration Studies and professor of sociology at the University of California-San Diego.