More than 20 million pounds of radioactive material are being shipped to the United States from China, according to a report published Monday by the American Association for the Advancement of Science (AAAS).

The report comes as President Donald Trump is considering imposing sanctions on Chinese officials for their alleged role in a massive cyberattack that hit major US corporations and government agencies in late May.

“The evidence shows that China is using a wide variety of technologies and practices to steal sensitive, classified information from US firms and businesses, including those owned by US government contractors,” said Richard C. Anderson, chief executive officer of the Association for Computing Machinery, which commissioned the report.

The Chinese government has denied responsibility for the attack.

A US government source told Reuters news agency that the US intelligence community was aware of the Chinese government’s alleged involvement in the attack but that the administration had not been briefed about it.

China, which is the world’s largest importer of American electronics, is known to have conducted cyber attacks against US firms, the government source said.

The US Congress and the White House have been in contact about the report and the possible sanctions.

Trump has expressed skepticism that China could be responsible for the cyberattack, saying in April he was not certain whether China had been behind it.

In the report, the researchers noted that the U.S. military is currently in the process of purchasing over 2,000 lithium-ion batteries that were shipped from China to the U: The batteries were originally made in the U and have been shipped in China for more than a decade.

The batteries are believed to be of high quality, but the report said they were also used in Chinese electronics, making it unlikely that they would pose a threat to the American market.

The report also said there is concern that Chinese manufacturers of some components of electronic devices could be producing counterfeit versions of them.

The batteries were manufactured by two companies in Guangzhou and Tianjin, which were both under government control, according the report; the companies did not respond to requests for comment.

The report said that there is evidence that some of the batteries were made in China but were shipped to other countries.