(Bloomberg) -- US government agencies have issued a new round of requests for information about Applied Materials Inc.’s shipments to Chinese customers, reviving a sensitive topic as Washington tries to sever sales of advanced chipmaking gear to its geopolitical rival.

Applied, America’s largest supplier of equipment for making semiconductors, disclosed “multiple subpoenas” as recently as February from agencies including the Securities and Exchange Commission and the US Attorney’s Office for the District of Massachusetts. That comes on top of requests from the Commerce Department and other agencies dating back to 2022, when the Biden administration escalated a campaign of sanctions to prevent the flow of advanced chips to China.

Applied, which didn’t elaborate on the most recent summons, is one of several US companies at the heart of efforts to contain China’s technological ascent. It provides much of the equipment central to the incredibly delicate task of fabricating semiconductors, and the US has sought its cooperation — as well as that of its peers — in that campaign. 

But last year, Reuters reported that the Justice Department had launched a probe into its dealings with Semiconductor Manufacturing International Corp. That company, China’s largest chipmaker, managed to make an advanced processor in 2023 for Huawei Technologies Co. that was previously thought beyond China’s reach, spurring a debate in Washington about the efficacy of trade sanctions.

“We are cooperating fully with the government in these matters,” Applied said in a filing Tuesday. “These matters are subject to uncertainties, and we cannot predict the outcome, nor reasonably estimate a range of loss or penalties, if any, relating to these matters.”

Despite sanctions, gear makers such as Applied are getting more of their revenue from China than ever before, given the country’s appetite for electronics and efforts to stockpile before stricter curbs kick in.

Read More: Chipmaking Gear Companies Get More Sales From China Than Ever

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