International students bring a wealth of diversity and a healthy chunk of money to many American colleges and universities.

But the flow of international students to the U.S. will most likely decrease in the fall. The coronavirus has hit the U.S. hard and may dissuade some international students from coming. Challenges and delays in obtaining visas to America, and in getting flights here, threaten the enrollment of some.

Trade conflicts and other tensions between the U.S. and some nations, particularly China, the biggest source of international students, might play into some students' decisions. Further, the number of international students enrolled in American colleges has already dropped over the past couple of years.

"There are just so many things out of our control," said Lina Stover, undergraduate admissions director at the University of Nebraska at Omaha.

Coronavirus crisis

Sue Zhang, a Chinese student who will graduate from the University of Nebraska-Lincoln this month, has decided to go to graduate school at UNL as well. But Zhang, who has majored in civil engineering and math, told the Omaha World-Herald she expects the coronavirus crisis to cut into UNL's international student enrollment.

Worry about getting COVID-19 compelled her to stay put at UNL. She had hoped to visit other graduate schools this spring, such as Stanford University and the University of California-Davis, but she didn't want to fly while the country was intensely affected by the virus.

"I think the university is doing everything they can," said Zhang, who moved with some other international students into UNL's Eastside Suites residence hall when the crisis closed many dorms.

A UNL professor in civil engineering, Dave Admiraal, said Zhang has a passion for learning and the ability to pick up new things quickly. "I have learned so much from them (international students) beyond what I would have learned had I only been exposed to students from the U.S.," he said in an email.

Zhang plans to start working on a master's degree in water resource engineering this summer. As for trade tensions and other conflicts between the U.S. and China, she said they aren't vital to her. "I'm just not that into politics," she said.

Declining student population

Last fall, UNL's international student population fell from 2,807 to 2,560, according to the UNL Factbook, an 8.8 percent decline. The coronavirus crisis may affect all universities' enrollments in the fall, said Josh Davis, UNL's associate vice chancellor for global affairs. It's too early to say how much, he said.

"International students really add so much to our campus and our community," Davis said. They enrich a campus's diversity and have become a key source of revenue to American colleges over the past 10 years. At UNL and Iowa State, they make up close to 10 percent of the enrollment, and many of them pay full out-of-state tuition.

Davis said UNL wants to stay in touch with international students who have stayed on campus or gone home. UNL holds virtual coffee talks, he said, and held a virtual karaoke night this semester. The students "are looking for the signal and message that they're welcome here," he said.

If visa challenges mean that some international students can't get back to Lincoln until the middle of the fall semester, Davis said, UNL will work with them.

'Three-plus years of rhetoric'

Grant De Roo, a higher education consultant in Iowa City, said "three-plus years of rhetoric that paints other countries as antagonists to the United States" has hurt international enrollment. President Donald Trump's talk about sealing borders, American nationalism and a travel ban for some nations give the U.S. an unfriendly image, he said.

"I think it's really fundamentally changing the way international students view the United States," he said.

Ryan Hamilton, executive director of the Nebraska Republican Party, disagrees. Trump insists that allies fulfill their financial obligations to international organizations like NATO and that Mexico strengthen its border, Hamilton said.

If those expectations make the U.S. seem less friendly and unwilling to be taken advantage of, "most Americans are prepared to accept" the consequences, he said.

Edna Chun, chief learning officer at the consulting firm HigherEd Talent, said delays in obtaining visas could make it difficult for some international students to come to the U.S. Greater scrutiny of visas is also a concern.

Chun cited a Palestinian student from Lebanon who enrolled at Harvard University last year. Immigration officials in Boston sent the student back to Lebanon when they found anti-American political messages from his friends on a laptop, according to multiple news accounts. The young man was ultimately allowed in.

The University of Nebraska at Kearney saw a slight decline in international students last year. Tim Burkink, UNK's assistant vice chancellor for international affairs, said he and his staff hope to retain many of their existing international students, about three-fourths of whom remain in Kearney.

Visa hangups "would probably be the biggest barrier" to coming to UNK, he said. Staff shortages at U.S. consulates and embassies in other nations -- American staffers have been brought back during the pandemic -- contribute to visa problems.

Burkink nevertheless said he is optimistic that the number of international students at UNK will be flat or only slightly down.

De Roo said competition for those students has increased in recent years. English-language nations such as Canada, Great Britain and Australia have upped their higher ed games to provide good degree programs for international students, he said.

Not everyone saw a decline last year. Wayne State College said its global enrollment increased last fall to 82 from 38. UNO's rose from 845 to 876.

Sue Zhang, who plans to be an engineer, said her parents hope that she will eventually return to China. Their wishes are a major consideration, she said.

But she could also imagine getting a job in the U.S. or getting married and staying here. "I was kind of thinking about it," she said. "Who will know what will happen later?"

This story was written by Rick Ruggles of Omaha World-Herald for the Associated Press.