Jay Bhattacharya, director of the National Institutes of Health (NIH), made the remarks during a Senate committee hearing examining both recent cuts to his agency and deeper reductions proposed by the White House in next year's budget.

Bhattachartya said he had created an appeals process for scientists and laboratories whose research was impacted, and that the NIH had already "reversed many" of the cuts.

"I didn't take this job to terminate grants," said the physician and health economist who left a professorship at Stanford University to join the Trump administration.

"I took this job to make sure that we do the research that advances the health needs of the American people."

The hearing came a day after more than 60 NIH employees sent an open letter to Bhattacharya condemning policies they said undermined the agency's mission and the health of Americans.

They dubbed it the "Bethesda Declaration" -- a nod both to the NIH's suburban Washington headquarters and to Bhattacharya's role as a prominent signatory of the 2020 "Great Barrington Declaration," which opposed Covid lockdowns.

Since Trump's January 20 inauguration, the NIH has terminated 2,100 research grants totaling around $9.5 billion and $2.6 billion in contracts, according to an independent database called Grant Watch.

Affected projects include studies on gender, the health effects of global warming, Alzheimer's disease, and cancer.

Trump has launched a sweeping overhaul of the US scientific establishment early in his second term -- cutting billions in funding, attacking universities, and overseeing mass layoffs of scientists across federal agencies.