Secretary of Health and Human Services Robert F. Kennedy Jr. defended President Donald Trump’s executive order spurring the domestic production of the weed killer glyphosate, as his Make America Healthy Again movement reels from the president’s embrace of the chemical they despise.

Trump on Wednesday night signed an executive order invoking the Defense Production Act to compel the domestic production of elemental phosphorus and glyphosate-based herbicides. Glyphosate is the chemical in Bayer-Monsanto’s Roundup and is the most commonly used herbicide for a slew of U.S. crops. Trump, in the order, said shortages of both phosphorus and glyphosate would pose a risk to national security.