The demands by Sen. Mark Warner (D-Va.) come in the wake of revelations that Facebook has for years allowed phone makers, including Apple and BlackBerry, to access personal data about the company’s users and about their friends.

The prospect of Huawei and ZTE having access to Facebook data is especially fraught from a privacy perspective given the often-tight connections between Chinese companies and the country’s surveillance-minded government.

In Tuesday morning remarks cited by the Washington Post, Sen. Warner cited the “ongoing threat these Chinese telecom companies pose.”

The remarks came after the Post reported Monday that Warner had asked Facebook to disclose whether it the company had provided Huawei and ZTE with access to customer data.

A spokeswoman for Warner confirmed the inquiry, and stated the senator made the request on Monday by email. Warner also expressed frustration on Tuesday that Facebook did not say whether or not it had let Huawei and ZTE access the data.

“I believe it’s a serious danger. I’ve been disappointed we’ve not gotten a straight answer,” he said, according to the Post, adding it would be “very surprising to me if [Facebook] somehow excluded the Chinese telecom providers.”

Facebook did not immediately respond to a request for comment.

In recent days, Facebook has been engulfed in a fresh privacy controversy after the New York Times reported the social network provided data access to over 60 device makers, including Samsung and Amazon. As Fortune’s David Meyer explained, the privacy implications are troubling:

“This means that the software of companies including Apple, Amazon, Samsung, Microsoft and BlackBerry gets to plug into Facebook’s systems and access data that does not belong to the specific person who’s using that software.

“The Times piece uses the example of BlackBerry’s Hub app, which aims to consolidate a user’s messages from various platforms—from Facebook notifications to Gmail emails—into one interface. A Times reporter logged into his Facebook account on that app, gaining access not only to detailed information about 556 friends, including sensitive stuff about religious and political leanings, but also to identifying information on 294,258 friends-of-friends.”

Facebook has attempted to play down the significance of its arrangement with the device makers, saying in a blog post that it disagreed with the New York Times‘ conclusions, and that the data access simply served to ensure Facebook was available on different operating systems.

Any revelation that Chinese phone makers had access to Facebook data could make it harder, however, for the company to sweep away the controversy. In recent months, Congress and the Trump Administration have repeatedly identified ZTE and Huawei as a potential threat to national security.