Russian President Vladimir Putin could rely on cryptocurrencies to evade the U.S. and other sanctions launched against the Kremlin for its invasion of Ukraine; a Treasury official told lawmakers Tuesday.

“Yes, senator, that’s possible,” Elizabeth Rosenberg, Treasury’s assistant secretary for Terrorist Financing and Financial Crimes, said when Sen. Elizabeth Warren, D-Mass., asked her if digital assets could be used to skirt sanctions.

The Senate Committee on Banking, Housing and Urban Affairs assembled the hearing to discuss Russia’s continued war on Ukraine, such as the seizure of assets from Russian oligarchs and the G-7 call to cap the price of Russian oil.

Warren said she’d worried that Russian elites use cryptocurrencies Russian to dodge sanctions since the country invaded Ukraine in February.

“Back then we already knew that countries like North Korea had used crypto to skirt sanctions and launder at least hundreds of millions of dollars. And Russia could easily be part of that,” Warren said.

The Treasury Department has already identified Russian entities attempting to circumvent sanctions with crypto. Twenty-two individuals and two entities, including a neo-Nazi paramilitary group, were designated this month for helping Russia digitally finance the war on Ukraine.

Russia-based Darknet Market Hydra and Garantex, a virtual currency exchange, were also sanctioned that month partly to cut off avenues for potential sanctions evasion.

But Russia had developed its own digital currency as early as February in hopes of trading directly with countries that will accept the funds without first converting to dollars. 

Warren mentioned that Coinbase, a leading U.S. cryptocurrency exchange platform, filed a lawsuit this month against the Treasury Department on behalf of Tornado Cash users.

Coinbase’s chief legal officer, Paul Grewal, told CNBC the sanctions set “a dangerous precedent,” but Rosenberg called them effective.

“When they can serve as a deterrent to any criminal (who) would seek to use a mixer in order to launder their funds, the proceeds of corruption or any criminal activity, that’s an effective avenue that we can use in order to signal that we cannot tolerate money laundering,” Rosenberg said.