In an open letter to German magazine Der Spiegel, former NSA contractor Edward Snowden calls U.S. and British intelligence agencies the “worst offenders” when it comes to mass surveillance.

In the letter, titled A Manifesto for Truth [click for full text], Snowden defends his decision to leak classified information that he claims has helped the world “[learn] a lot in a short amount of time about irresponsibly operated security agencies and, at times, criminal surveillance programs.”

Snowden claims that cries for surveillance program reforms justify his decision to leak classified information and accuses the U.S. government of “systemic violations of law” and of “criminalizing political speech.” Though his most scathing criticism is directed toward U.S. and British intelligence programs, Snowden writes, “We cannot forget that mass surveillance is a global problem and needs a global solution.”

"Citizens have to fight against the suppression of information about affairs of essential importance for the public," Snowden claims. "Those who speak the truth are not committing a crime."

But U.S. official see it differently. Though the White House has not yet responded to Snowden’s claims, White House Senior Advisor Dan Pfeiffer said Sunday on ABC’s “This Week” that Snowden has violated U.S. law and should return home to face justice. He also insisted that there has been no discussion of granting Snowden clemency.