"The answer is that we do not know," Milley said during a press briefing, while speaking about the possibility of whether the virus originated in a laboratory or in a wet market in Wuhan, China, or somewhere else.
Milley said that existing evidence suggests the virus is natural, rather than manmade, and its was likely not released intentionally.
"We do not have conclusive evidence on any of that, but the weight of evidence is that it was probably not intentional," he said.
Milley called on the Chinese government to cooperate and allow US inspectors and investigators access Wuhan and try to find out the reasons of the COVID-19 pandemic.
Earlier on Tuesday, US President Donald Trump promised to trace the source of the novel coronavirus and publicly release the findings. Trump has criticized China for concealing the COVID-19 outbreak and mismanaging the crisis at its initial stages. The US president continues to claim that intelligence data suggests that the novel coronavirus leaked from a lab in the city of Wuhan.