The possibility that NSA leaker Edward Snowden could defect to China - or cooperate in any way with Chinese authorities - is a top concern for U.S. intelligence officials.

For the ABC/Yahoo Power Players interview series, I did a " Politics Confidential " interview this morning with a former top Obama Administration official who knows as much about his as anybody: former CIA and Pentagon Chief of Staff Jeremy Bash. He says Snowden's brain - his knowledge of how our intelligence systems work - would be more dangerous in the hands of a foreign government than any documents he has leaked.

Related: U.S. Fears Snowden May Defect to China

See the full interview with Bash on Friday, but here's the key exchange on China -

KARL: Let's talk about Snowden. So this guy's on the run-he says still in Hong Kong-and he's claiming that he's got a heck of a lot more classified information which he's ready to divulge. How worried are our intelligence officials about what more he could say?

BASH: The authorities are worried about multiple things. Right now, they want to know, what else does he have? What else did he take from NSA? What else might he have on his person? Maybe he uploaded some documents, maybe he has them in electronic format. Second, did he have any other accomplices? Did anybody else help him pull this off? And third, what might have fallen into the hands of a foreign government? Perhaps the Chinese, maybe advertently, maybe inadvertently. And one of the things you see now is he's out there making threats that the Chinese government or other governments are going to learn about many of the things that he knows, perhaps hacking into Chinese systems. Jon, that's an old form of graymail.

That's where someone accused of doing something inappropriate basically goes back to law enforcement and goes back to the intelligence agencies and says, "I've got more secrets, and, unless you lay off me, I'm going to spill those secrets."

KARL: So, let's take that last one first. So, China. I mean, let's say he went effectively double agent- went over to the Chinese. How much damage could he do?

BASH: Oh, I think he could do tremendous damage. I think if a foreign government learned everything that was in Edward Snowden's brain, they would have a good window into the way we collect signals intelligence. His job, as a Booz Allen contractor working at NSA Hawaii, was, as he said, an infrastructure analyst. What does that mean? That means that his job was to analyze the telecommunications infrastructure around the world to figure out where NSA could pull signals intelligence from. He had access to very sensitive information. He had access to highly classified information. He's not a whistleblower by the way because a whistleblower actually wants the rule of law to be enforced. He copied documents, and he made a run for it. So, he's not a whistleblower and, in fact, it may be worse. He may be actually aiding our enemies.