The US Senate confirmed the appointment of President Joe Biden of Janet Yellen as secretary of the Treasury. As Secretary of the Treasury, Yellen will be responsible for several agencies that deal with cryptocurrencies, the most notable being the Financial Crimes Enforcement Network (FinCEN) and the Currency Controllership (OCC).

Yellen, who ran the Federal Reserve from 2014 to 2018, said "not a fan" of Bitcoin and referred to the asset as "highly speculative".

More recently, during the confirmation process for the Treasury function, Yellen updated her ideas on cryptocurrencies, stating that she believes they can benefit the financial system.

In an oral testimony before the Senate Finance Committee, Yellen responded to a question about cryptocurrencies being used to finance terrorism, saying that regulators and legislators should "examine ways in which we can reduce their use", at least with regard to illicit purposes.

In her written testimony she was more comprehensive on the subject: "I think it is important to consider the benefits of cryptocurrencies and other digital assets and the potential they have to improve the efficiency of the financial system," she wrote.

While cryptocurrencies can be used for terrorism and money laundering, she said, "I think we need to look closely at how to encourage their use for legitimate activities and, at the same time, restrict their use for evil and illegal activities."