Commodity Futures Trading Commission Chairman Christopher Giancarlo sent Senate Agriculture Committee leaders a six-page letter detailing CFTC’s oversight of digital currency systems such as bitcoin.

The letter was written in response to questions Senate Agriculture Committee Chairman Pat Roberts, R-Kan., and ranking member Debbie Stabenow, D-Mich., posed in a letter to Giancarlo last week.

“American taxpayers deserve strong safeguards against fraud, manipulation, and abusive practices in the futures and options markets,” wrote Roberts and Stabenow. “The CFTC plays a critical role in protecting customers and the markets from harm.”

They noted that, in December, three U.S. futures exchanges announced the launch of the first bitcoin futures and options, and while bitcoin gained popularity, “it has also experienced significant market volatility.”

Giancarlo noted that while the CFTC does not directly oversee spot virtual currency markets, the Commodity Exchange act “grants the commission authority to take enforcement action for fraud and manipulation in connection with commodities in interstate commerce.”

He also told them the CFTC “has been in constant, active coordination with other regulators concerning cryptocurrencies,” and has had discussions with foreign regulators as well “to coordinate efforts and share information about bitcoin futures products and oversight and surveillance issues.”