Senator John McCain (R-AZ) said on "State of the Union" Sunday morning that if he were former Defense Secretary Robert Gates, he would have waited to publish memoirs critical of the president and decisions about the Afghan War.

"He's obviously very frustrated—which surprised all of us who know him—and he's decided to really let loose," McCain said of Gates, whose forthcoming memoir Duty provoked cable news controversy this week.

"But was it appropriate?" host Candy Crowley asked of the timing of the book.

"I think, frankly, if I would have been giving him advice, I would have waited," McCain replied. "As far as waiting until it is over in Afghanistan, I wouldn't have done that. But maybe, a retrospect of a little longer than now. But I also respect his ability to voice his views any time he wants to."