Graduates at Liberty University in Lynchburg, Va. (Brendan Smialowski/AFP/Getty Images)
Columnist

President Trump is obsessed with trade surpluses. In his zero-sum view of the world, if we don’t sell more than we buy in a given industry, we must be losing.

Yet he seems hellbent on destroying one of our winningest exports: higher education.

Unlike with toys or televisions, the United States sells much more higher education to the rest of the world than we buy from it. In fact, the United States hosts the largest number of international students worldwide. More than twice as many foreign students come here as we send abroad.

In dollar terms — since that seems to be what Trump cares about — foreigners spent about $39.4 billion purchasing U.S. educational services in 2016, whereas Americans purchased about $7.5 billion in education imports, according to ­Bureau of Economic Analysis  data.

That means we have an educational trade surplus of nearly $32 billion. For context, that is relatively close to our trade surplus in completed civilian aircraft. And the figure doesn’t include what international students spend here on food, housing, books and the like.

Lest you think these international kids are somehow displacing or otherwise hurting more deserving homegrown applicants, note that they typically subsidize local students. Public schools have partially offset enormous state funding cuts by enrolling more out-of-state and international students, who can be charged double or even triple the tuition of their in-state peers.

Even lower-ranked schools have generally had little trouble recruiting these full-freight-paying foreign applicants. After all, we have the best higher-education system in the world, particularly in fields such as science and technology. Roughly half  of international students who come here study those subjects; only about a quarter  of degrees awarded overall in the United States are in science and engineering.

And so, with the exception of a few years following 9/11, international enrollment has climbed consistently for decades.

Until now.

Multiple reports show the spigot of international students has been turned off.

A new National Science Foundation report, for instance, found that the number of international students enrolled at U.S. universities declined last fall by close to 4 percent from the previous year, from 840,160 to 808,640.

Astonishingly, more than half of that decline came solely from lower enrollment of Indian graduate students in science and engineering fields, as a ­National Foundation for American ­Policy analysis observed.

A separate survey of colleges released in November by the nonprofit Institute of International Education also found declines  in new international student enrollment. Among the top reasons reported for the drop were “feeling unwelcome in the United States” and visa issues.

Newly released State Department data likewise showed a decline in the number of new student visas awarded in the fiscal year ending in September 2017, which bodes ill for enrollment this year.

To be clear, we don’t actually know to what extent fewer new international students are arriving here because they’re being denied visas, or because they are preemptively choosing not to come — and, if the latter, why. 

Developments overseas can make a difference: Saudi Arabia, historically a big feeder to U.S. schools, pulled back scholarship funding. Indian currency devaluation made rising U.S. college tuition even less affordable.

And U.S. schools face more competition from other countries, such as Canada, that have decided to compete for global talent by advertising lower ­tuition, faster visa processes and surer opportunities to stay after graduation.

Meanwhile, the United States has been broadcasting a different message. 

The so-called Muslim ban, attempts to halve legal immigration levels and plans to eliminate the ability of spouses to work while awaiting green cards have all told international students to steer clear.

Additional policy measures are likely coming, as well.

The Trump administration has indicated it will pass a new rule that either eliminates or sharply curtails the ability of international students to work here in the months after graduation. And the administration is reportedly considering new limits on visas for Chinese students. China is our largest feeder of international students, accounting for more than 30 percent of international enrollment.

Not to mention all the other bad PR American schools are getting, thanks in part to other kinds of policy failures.

“If you have a mass shooting every day in America, and had this for three years, people begin to say, ‘Is my daughter or son going to be safe here?’ ” says Allan E. Goodman, president of the Institute of International Education. Stories about bridges collapsing and campus rape are also not helping, he says.

There are a lot of things government, at all levels, can do to make sure one of our most successful export industries continues to succeed. Instead, at virtually all levels, our political leaders are doing the opposite of those things.