Former U.S. Attorney General Eric Holder says Edward Snowden performed a "public service" in stoking a national debate about secret domestic surveillance programs, but that he should still return to the U.S. to stand trial.

As a National Security Agency contractor, Snowden leaked details in 2013 of the U.S. government's warrantless surveillance of its citizens before fleeing the country. He now lives in Russia and faces U.S. charges that could land him in prison for up to 30 years.

Holder says Snowden's leaks harmed American interests abroad and put intelligence assets at risk. But Holder adds that whatever punishment Snowden receives should be weighed against the "usefulness" of a national debate about the government's secret surveillance programs.

Holder spoke with CNN political commentator David Axelrod in a podcast released Monday.