The United States Department of Energy is now saying the COVID-19 pandemic most likely came from a laboratory leak in China.

A senior U.S. intelligence official told the Wall Street Journal that new information caused the Department of Energy to make the updated assessment.

The New York Times reported that some officials briefed on the intelligence said that it was relatively weak and that the Energy Department’s conclusion was made with “low confidence,” suggesting its level of certainty was not high.

The intelligence community has noted repeatedly that a lack of cooperation from Beijing has made it difficult to get to the bottom of where COVID-19 originated.

Government officials have been divided over the origin of the pandemic since it began. 

The World Health Organization concluded in 2021 that it was “extremely unlikely” COVID-19 might have spilled into humans in the city of Wuhan from a lab. Many scientists suspect the coronavirus jumped into people from bats, possibly via another animal.

However, WHO’s expert group of scientists said last year that “key pieces of data” to explain how the pandemic began were still missing.

Identifying a disease’s source in animals typically takes years. It took more than a decade for scientists to pinpoint the species of bats that were the natural reservoir for SARS, a relative of COVID-19.

On Monday, China’s government rejected the Energy Department’s assessment and accused the agency of engaging in a political smear, the Wall Street Journal reported.