Target's recent data breach should appear as a warning to American leaders and citizens about the threat posed to the United States by cyber attacks, retired Adm. Mike Mullen said Tuesday.

"Cyber scares me to death," Mullen said at a breakfast hosted by The Weekly Standard and Concerned Veterans for America. "It almost has no bounds."

Mullen listed cybersecurity as fourth on his personal list of top five problems facing the United States, with the other four (in order) being the national debt, the K-12 education system -- "it's still in very bad shape," he said -- "political paralysis" in Washington, and the plight of veterans, especially those returning from Iraq and Afghanistan, who are culturally isolated from civilians and face a difficult job market.

Hackers stole the information of 70 million Target shoppers in the United States, including about 700,000 Canadian customers, according to the company. The malware used in the hack originated in Russia.

While on the cybersecurity topic, Mullen discussed NSA leaker Edward Snowden, as well.

"I hate what Snowden did, I think that Snowden's a traitor," he said, although he allowed that the leaks had instigated a beneficial conversation about cybersecurity and government activity. Prior to the leaks, Mullen said he had feared that a "cyber 9/11" would prompt hasty changes to law without that conversation taking place.

House Intelligence Committee Chairman Mike Rogers, R-Mich., suggested Snowden collaborated with Russian spies in his efforts. Rogers emphasized that Snowden's leaks range beyond -- indeed, wasn't even primarily concerned with -- privacy issues.

"This was a thief, who we believe had some help, who stole information the vast majority [of which] had nothing to do with privacy," Rogers said Sunday on NBC's "Meet the Press."

"If it was a privacy concern he had, he didn't look for information on the privacy side for Americans," Rogers also said. "He was stealing information that had to do with how we operate overseas to collect information to keep Americans safe."