Asked Sunday on CNN if he thinks President Obama "has made Americans less safe," former Vice President Dick Cheney said: "I do."

Looking slimmer and relaxed, Cheney told John King on "State of the Union" that Bush administration policies on detention and interrogation of suspected terrorists – some of which were immediately modified by Obama — "were absolutely essential" to preventing another 9/11-style attack.

"I think that's a great success story. It was done legally. It was done in accordance with our constitutional practices and principles," the former vice president said. "President Obama campaigned against it all across the country. And now he is making some choices that, in my mind, will, in fact, raise the risk to the American people of another attack.

Cheney said the Bush administration "made a decision after 9/11 that I think was crucial: We said, 'This is a war. It's not a law-enforcement problem.'"

"When you go back to the law enforcement mode, which I sense is what they're doing – closing Guantanamo and so forth – that they are very much giving up that center of attention and focus that's required, and that concept of a military threat that's essential if you're going to successfully defend the nation against further attacks," he continued.

The former vice president, who now has a BlackBerry, said he plans to spend "the bulk" of his time in the next few months working on a book.

Cheney said he has talked with President Bush three times in recent weeks, and has expressed displeasure that his aide Scooter Libby – whose sentence on charges of perjury and obstruction of justice was commuted — was nevertheless left "sort of hanging in the wind" without a full pardon.

"I think he's an innocent man who deserves a pardon," Cheney said.

The former vice president noted that radio host Rush Limbaugh has challenged Obama to a debate.

"Hell, I'd pay to see that," Cheney said. "I think Rush is a good man and serves a very important purpose."