A group of more than 200 HIV scientists and researchers have come out against the drastic cuts President Trump has proposed for major global AIDS programs.In an open letter made public Wednesday on the final day of the annual Conference on Retroviruses & Opportunistic Infections in Boston, the co-signers say they’re “gravely concerned” about reductions to global AIDS programs in the FY-19 budget request.

“Science shows us that we can defeat HIV, but not if we defy evidence,” the letter says. “President Trump’s misguided budget proposal, and his administration’s attempts to scale up policies in defiance of evidence will only undermine the global AIDS response and should be stopped.”

Trump’s proposed budget calls for varying reductions to domestic and global HIV/AIDS programs, but the global initiatives bare the brunt of the cuts.

The President’s Emergency Plan for AIDS Relief, or PEPFAR, would see a reduction of 17 percent compared to existing funding levels, down from $4.65 billion in FY-17 to $3.85 billion.

Contributions to the Global Fund to Fight AIDS, Tuberculosis & Malaria would be cut a whopping 31 percent. While the current level is at $1.35 billion, Trump’s request calls for $925 million in funds.

Taken together, Trump’s budget has at least $1.23 billion in cuts to global HIV programs. In contrast, the letter says “a surge in global AIDS funding is needed” to control the epidemic by 2030.

The signers of the letter are HIV scientists and researchers from across the globe. Among them is Françoise Barré-Sinoussi, a French virologist who won the Nobel Prize in 2008 for work identifying HIV as the cause of AIDS.

The letter also takes issue with Trump’s reinstatement of the Mexico City policy, which bars U.S. funds for non-governmental organizations that work overseas and provide abortion counseling or advocate to decriminalize the procedure. According to the letter, expansion of the policy to include PEPFAR “will reduce the standard of sexual and reproductive care provided to women living with and at risk for HIV.”

Also cited in the letter is the new Conscience & Religious Freedom Division within the Department of Health & Human Services. Critics have decried the agency as a tool for anti-LGBT discrimination based on the perception it would enable medical providers to refuse services to LGBT people or people with HIV.

Additionally, the letter takes issue with funding levels proposed for the National Institutes of Health, which conducts HIV/AIDS research. In particular, proposed funds for the National Institute for Allergy & Infectious Diseases, or NIAID, and the Fogarty International Center are cited as concerns.

According to the letter, the cuts would “slow urgently needed HIV basic and implementation research and impair work to build research capacity in partner nations to fight HIV.”

It remains to be seen if Congress will agree to Trump’s proposed cuts for global AIDS programs. After the administration sought similar cuts last year, Congress kept the funding as it had been in years past.

The White House deferred comment on the letter to the Office of Management & Budget, which didn’t immediately respond to a request to comment.