The Trump administration is blocking all funding that flows to outside health researchers—billions of dollars that would have gone to study diabetes, cancer and more.

The pause came in the form of a footnote from the Office of Management and Budget Director Russell Vought’s office, in a document that doles out federal funds to the National Institutes of Health. The footnote stipulated that the agency’s funding for the remainder of the fiscal year could only go to staff salaries and expenses, not to new grants or certain grants that are up for renewal. Most NIH-funded research is done by outside scientists at labs across the country.

The footnote puts a halt on roughly $15 billion in NIH funding, according to an estimate from the office of Sen. Patty Murray (D., Wash.), vice chair of the Senate Committee on Appropriations.

“This outrageous decision to prevent NIH from spending the funding that Congress has explicitly provided for medical research must immediately be reversed—life-changing cures and patients’ prognoses hang in the balance,” Murray said.

“It’s a huge deal,” said Jeremy Berg, a former institute director at the NIH. “I can’t imagine any reasonable rationale for doing this other than the desire to do damage to NIH and biomedical research.”