Sen. John McCain (R-Ariz.) began his questioning of defense secretary nominee Chuck Hagel by pressing the nominee on his opposition to the 2007 troop surge in Iraq. McCain asked Hagel whether he still believes that the surge was, as Hagel said at the time, "the greatest foreign policy blunder since the Vietnam War."

"I'm not going to give you a yes or no answer," Hagel responded.

McCain, who used to be a close friend of Hagel's, was not satisfied. He kept pressing Hagel. But Hagel refused to budge.

"I'll defer that judgment to history," he said.

Hagel then went on to explain why he thought the initial decision by President George W. Bush to launch the war against Iraq was a mistake. Hagel cited the loss of American "blood and treasure," and he noted that the war took the focus of the U.S. military off the war in Afghanistan.

Hagel said the decline in violence in Iraq was due to more than "flooding the zone" with more U.S. troops. He cited the uprising of Sunni Muslim tribesmen as being another instrumental factor.

McCain insisted the surge was "the fundamental factor" in turning around the war, and he called Hagel's stance on the surge "a fundamental difference of opinion."

"I think history has already made a judgment about the surge and you're on the wrong side of it," McCain said. The Arizona senator said Hagel's view on the Iraq surge would influence his decision about whether to vote for his confirmation. He has not indicated yet whether he will vote for or against Hagel.