With a proclamation issued Monday, President Donald Trump is extending and expanding immigration restrictions to limit the entry of new foreign workers. The move set off ripples of alarm among scientists and drew fire from experts concerned about the future of US science.

According to the order, the United States will stop issuing certain categories of foreign worker visas— notably the H-1B visa given to foreign faculty hired at universities and employees hired by tech firms— until the end of the year. The Trump administration on Monday characterized the decision as a plan to stave off the economic impact of the coronavirus pandemic, and to prioritize American jobs.

The freeze, which goes into effect 24 June, will not apply to people who are currently in the United States, or those with other valid documents for entering the country. It provides exemptions for some foreign workers— academics on J-1 visas should be clear according to a senior administration official. Officers issuing visas at US consulates abroad will weigh petitions for other exemptions, including from researchers or doctors engaged in COVID-19 research.

Experts slammed the move and argued that foreign talent was necessary to keep the US science enterprise competitive.

“This is a huge deal,” says Julia Phillips, a member of the US National Science Board and former chief technology officer at Sandia National Laboratories in Albuquerque, New Mexico. The United States issued over 188,000 H-1B visas in 2019 across sectors, according to the US Department of State. According to a January report from the National Science Foundation , 30% of people in science and engineering jobs in the United States were born outside the country.

“We find it extremely concerning, particularly as medical residents are brought in on H-1B visas, and faculty who are necessary to educate the US workforce,” says Lizbet Boroughs, associate vice president for federal relations at the Association of American Universities, whose members include top US research schools.

“The bottom line is that suspending processing for H-1B visas is going to have an impact on American research and American innovation and America’s ability to train and teach its scientific workforce pipeline.”

‘Limbo is a good term’

For students, postdoctoral fellows, and faculty from overseas the move adds fresh uncertainty and anxiety to an already tumultuous 2020. In April, citing economic damage from the pandemic, the administration paused issuing green cards for people outside the United States, exempting medical workers. The new order extends that suspension into the end of the year and adds new categories of visas that will be restricted.

“A lot of people are trying to figure out what this means, how they are going to be personally affected,” says Mehmet Doğan, a physicist at the University of California, Berkeley and a Turkish citizen, who is part of an immigration working group at the UC student workers union. Doğan himself is awaiting an H-1B visa, but with the new rules, the path ahead is unclear.

“It is really sad that when this country has so many of the greatest research institutions in the world, greatest universities in the world, that when something like a pandemic happens, one of the first things the government does is to blame international researchers for unemployment,” Doğan says. “That’s crazy, but it’s also very sad.”

Lewis Bartlett, an infectious disease biologist at the University of Georgia in Athens, is among those trying to sort out his future. A UK citizen, he applied earlier this year for an H-1B visa to continue his work on the ecology and evolution of infectious disease in agriculture, particularly to support US beekeeping. He is hoping to have his H-1B application approved before his current immigration approval expires. But the new executive order has thrown the whole application process — already delayed by the pandemic — into question. “There is a lot of uncertainty,” he says. “Limbo is a good term.”

The ongoing string of immigration regulations is taking a toll on the students and postdocs who work in the lab of pancreatic cancer researcher Anirban Maitra at the University of Texas MD Anderson Cancer Center in Houston. Seventy percent of the 14-person group comes from outside the United States. “Every day there’s a new rule,” he says. “It’s just continuous stress.”

How the rules will be applied once consulates open and begin processing visa applications remains to be seen. In the meanwhile, the measures send a clear message, says Phillips. “You may be the most brilliant student anywhere. If you were not born in the US, there are absolutely no guarantees whether you will have any option to remain.”