Deputy Attorney General Rod Rosenstein was silent on the resignation of the deputy FBI director late on Monday, but he was vocal on the need to protect America’s digital economy from hackers and criminals.

At a late afternoon panel at the State of the Net internet policy conference in Washington, Rosenstein spoke about cyberthreats and emerging technologies. He said the challenge is daunting. 

“Our federal agencies are very much engaged, working on their own and working in coordination with industry to combat these threats,” he said. “Some of them are from foreign state actors, espionage efforts; some of them are commercial hacking efforts; some of them are criminals who are out to extract ransom, or extort corporations . . .  That’s the biggest challenge we face, is that we need to continue to improve our cyberdefenses so that we can help the private sector protect themselves against these intrusions.”

Watch: Three Things to Watch During Trump’s First Official State of the Union

Rosenstein said it’s important for the Department of Justice to make sure it is hiring people who can keep up legally and technologically with ever-evolving threats. 

“These are things that we didn’t learn in law school, literally, because it didn’t exist when many of us were in law school,” he said. “And so it really does require a focused effort by the Justice Department, the FBI and other federal agencies to make sure that we’re hiring people with the right expertise, and that we’re providing the appropriate training so that we’re keeping up on emerging technologies and [so that] we have a sense of where the vulnerabilities are.” 

Rosenstein also spoke about the challenges the department faces when it comes to cryptocurrencies, which have been used by people and organizations to illegally launder money and assets. 

“Well, obviously, cryptocurrencies serve some legitimate objectives, but like most emerging technologies, criminals are often the first to jump on the bandwagon,” he said. “So criminals see cryptocurrencies as an opportunity to move money without the ability to be detected, and therefore to protect the proceeds of money-laundering activities.” 

Rosenstein also said another challenge is that cryptocurrencies provide an opportunity to conceal income from taxation. 

Before the conversation began, the panel’s moderator announced that Rosenstein would not be taking questions outside the scope of his conversation onstage. Rosenstein was not asked about FBI Deputy Director Andrew McCabe’s resignation Monday.