President Donald Trump’s science adviser Dr. Scott Atlas on Monday has resigned from his position in the White House. 

A source with knowledge of the conversation said the Stanford University neuroradiologist left his job after his temporary government assignment. Atlas, who confirmed the news in a tweet, had no formal experience in public health or infectious diseases prior to his tenure at the White House. 

“Throughout my time at the White House, it was an honor to work with several selfless colleagues in designing specific policies to heighten protection of the vulnerable while safely reopening schools and society,” he wrote in a statement. “I remain highly optimistic that America will thrive once again and overcome the adversity of the pandemic.”

Atlas had previously clashed with top health officials, including infectious disease expert Dr. Anthony Faui, as he opposed stricter restrictions to curb the spread of the novel coronavirus pandemic. 

Weeks ago, the controversial Stanford University neuroradiologist encouraged Michigan residents to “rise up” against the state’s coronavirus restrictions. He once argued that masks did not prevent infection and that children cannot spread the virus. 

His argument prompted Stanford University to issue a statement that said Atlas’ views were “inconsistent with the university’s approach” to the pandemic. 

Atlas was hired as a special government employee. His service to the government was limited to 130 days in a calendar year, the San Francisco Chronicle reported.