Details are emerging on which fiat currencies might back the Libra stablecoin.

Bloomberg reported Monday that Facebook wrote a letter to U.S. Senators about Libra, addressing concerns over potential Chinese influence on the cryptocurrency. Sen. Mark Warner (D-Va.) previously wrote to Facebook asking the company to exclude the Chinese yuan from the basket of assets backing the Libra stablecoin.

“Any decision whether to add a new currency to the Libra Reserve would be made based on all the facts and circumstances at the time, including any direct or indirect regulatory restrictions,” Facebook reportedly wrote, adding that the decision would be made by the Libra Association, not Facebook itself.

According to Bloomberg, Facebook prov