China has come under increasing global pressure over lack of transparency in its handling of the Covid-19 pandemic, which has so far infected over 2.5 million people and claimed more than 170,000 lives across the world.
Ever since the virus came to light in Wuhan in December last year, speculation has been rife on whether the viral strain originated from the Wuhan Institute of Virology (WIV) or from its nearby Huanan Seafood Market.
"The burden's really on the Chinese to come forward with real evidence about where this virus developed," O'Brien said on Tuesday in an interview with Hugh Hewitt.
"The Chinese, the whistleblowers have disappeared. The media's been kicked out. Offers to send the CDC (Centers for Disease Control and Prevention) and other Western experts to come look into the issue have been rejected by the Chinese. So the burden's really on the Chinese to let us know how this virus developed. We'll have to watch and see what they do," he said.
"Look, there are two labs in Wuhan. There's the wet markets, and look, the burden is on the Chinese. There are already lawsuits that have been filed by, I understand, in the US. I think there are other governments that are looking into establishing liability against the Chinese for this," he said.
A wet market sells fresh meat, fish, produce, and other perishable goods as distinguished from "dry markets". It gets its name from the floors being constantly wet from the spraying of fresh produce and cleaning of meat and seafood stalls.
A wet market in the central Chinese city of Wuhan is believed to be the source of the coronavirus pandemic that began in December last year, crossing from animals to humans.
"And whether it came from the labs or it came from the wet markets, I mean, neither one of those is a good story, right? I mean, these wet markets are just horrific with the exotic animals being eaten and consumed on premises, and bats being sold and put into soup," he said.
O'Brien said that at least four viruses now have come out of China since 2000. "We've had this, what the Chinese called the Wuhan pneumonia and is now being referred to as the Coronavirus. We had SARS. We had the H1N1 swine flu...they've had the Avian flu," he said.
"I mean, we keep having these plagues unleashed on the world from China. It's very expensive. And whether they're coming from the wet markets or a lab or some other place, we need to get to the bottom of it," he said.
China needs to open up to the public health professionals who can come in and work on this to make sure it doesn't happen again, the top American national security official said.
He also claimed that the number of deaths being reported by China due to coronavirus is not accurate.
"We've got very good transparent numbers coming out of Singapore. So if you contrast China to other Asian countries that have a free press and that are committed to transparency, there's just a big difference. So it's hard to know. We just can't say what's actually happening in China," O'Brien said.