Appearing on ABC’s “This Week” Sunday, the Guardian’s Glenn Greenwald promised to bolster the most extreme claims of former NSA infrastructure analyst and contractor Edward Snowden:

The fugitive leaker stated in the first publicly revealed video of an interview with Greenwald that, “I, sitting at my desk, certainly had the authority to wiretap anyone, from you or your accountant, to a federal judge or even the president, if I had a personal email.”

ABC’s George Stephanopoulos highlighted that statement, and Greenwald promised to vindicate it, saying he defied NSA officials—set to testify before the Senate Wednesday—to deny that surveillance programs work in this manner. He also mentioned previously reported examples of NSA abuse, calling for a rigorous investigation in the wake of Snowden’s leaks.