The chairman of the U.S. Securities and Exchange Commission (SEC), Jay Clayton, says his agency is taking a "measured" regulatory stance on "promising" blockchain tech.

Giving testimony on the oversight of his agency before the Senate Committee on Banking, Housing and Urban Affairs on Tuesday, Clayton honed in on its regulation of the crypto and blockchain space, saying the SEC has been dedicating "a significant amount of attention and resources on digital assets."

"Overall, I believe we have taken a measured, yet proactive regulatory approach that both fosters innovation and capital formation while protecting our investors and our markets," he said.

Clayton also spelled out how it's been enforcing securities rules on digital asset firms that stray over the line.

"This past year, the Commission has brought actions against a number of issuers of digital assets for allegedly engaging in fraud and for violating the registration provisions of the federal securities laws," he said. "The Commission also filed charges related to the unlawful promotion of initial coin offerings (ICOs) and the unlawful operation of a digital asset trading platform."

Also indirectly cited was the SEC's ongoing court action against Telegram.

The commission took "emergency action to block an alleged unregistered, ongoing, public digital token offering in the United States that has raised more than $1.7 billion of investor funds," said the chairman.

While such enforcement actions are somewhat controversial in the crypto space, including another against Kik over its $100 million ICO, the SEC has also approved a number of initiatives it deems as falling within its rules.

For the first time, the SEC issued a “no-action” letter to TurnKey Jet, Inc. in April, agreeing that tokens used by the business-travel startup are not securities as long as the firm stays within certain conditions.  Similarly, in October, the SEC granted Paxos Trust Company no-action relief to settle equity securities trades on a blockchain platform for broker-dealers.

In addition, last week the New York Digital Investment Group (NYDIG) secured approval from the regulator to offer institutional investors shares of a new fund focused on bitcoin futures.

The agency's long-term reluctance to approve any of a number of bitcoin exchange-traded fund proposals has been criticized by industry executives. However, the SEC is sticking to its view that bitcoin isn't yet mature enough to support an ETF.