The Department of Homeland Security report said the country "intentionally concealed the severity of COVID-19" in early January.
During that time, officials said China was also building out its own stockpile of medical supplies and took steps to protect it.
The virus was first identified outside of the Chinese city of Wuhan in December 2019, and by mid-January, and the surrounding Hubai providence became the epicenter of the coronavirus outbreak.
At that time, China reported to the World Health organization that the virus showed "no clear evidence of human-to-human transmission," according to a Jan. 14 WHO tweet.
Preliminary investigations conducted by the Chinese authorities have found no clear evidence of human-to-human transmission of the novel #coronavirus (2019-nCoV) identified in #Wuhan, #China🇨🇳. pic.twitter.com/Fnl5P877VG— World Health Organization (WHO) (@WHO) January 14, 2020
But according to the intelligence report, exports from China dropped significantly as the country cornered off supplies, disrupting the global supply chain for nations that needed those essential items most.
"We further assess the Chinese government attempted to hide its actions by denying there were export restrictions and obfuscating and delaying provision of its trade data ... trade data shows that China likely stockpiled medical supplies for domestic use before its official notification to the World Health Organization that COVID-19 was contagious," the report said.
A Homeland Security analysis shows China produces about 80% of the world's surgical face masks but 48% fewer were shipped out during that time period. Exports on gloves dropped 48% and ventilator exports dropped 45%.
This report comes as the rift between the U.S. and China deepens. President Donald Trump once praised China's handling of the outbreak, saying President Xi Jinping was "doing a very good job with a very, very tough situation."
Now, the president is stepping up on attacks, placing blame for the virus on China.
"We are not happy with China. We are not happy with that whole situation because we believe it could have been stopped at the source, it could have been stopped quickly, and it wouldn't have spread all over the world," he said last week.