Three Democratic lawmakers in the House are demanding answers from Elon Musk about a recent “platform manipulation campaign” related to recent protests in China. In a letter to the Twitter CEO, Representatives Raja Krishnamoorthi, Adam Schiff and Jackie Speier write that they have “deep concern” about the recent spam campaign that drowned out tweets about the protests.

The lawmakers want Musk to answer questions about whether Twitter has any evidence the spam campaign was a state-backed effort by the People’s Republic of China (PRC). “To ensure that the United States is prepared to counter, thwart, and deter foreign influence threats online, it is critical that we understand the extent of the PRC’s potential manipulation of Twitter and identify how recent changes at Twitter are affecting the threat of CCP foreign influence operations on social media,” they write.

The lawmakers also address recent changes at Twitter under Musk’s leadership, with questions about what Twitter’s “emphasis on free speech” means for information access on the platform; as well as whether the company has the “capacity” to identify platform manipulation campaigns.

Since Musk took over Twitter, questions have swirled about how he will handle the platform’s dealings with Chinese officials, such as requests to remove “state affiliated” labels from their accounts. Tesla, the other company Musk runs, is highly dependent on China for manufacturing.

So far, Musk hasn’t publicly acknowledged the letter, which provides a December 31st deadline for a response. Twitter no longer has a communications team. However, Musk has shown little regard for other letters from lawmakers. He recently addressed a letter from Massachusetts Senator Ed Markey about Twitter’s failure to stop impersonation attempts with a dismissive tweet.