A testy exchange erupted on Thursday between Sen. John McCain and Joint Chiefs Chairman Gen. Martin Dempsey during the latter's testimony about September's deadly attack on the U.S. diplomatic mission in Benghazi, Libya.

"Gen. Dempsey, I was just going over your written statement and I have to admit it's one of the more bizarre statements that I have ever seen in my years in this committee," McCain said, referring to the Senate Armed Services Committee.

Thursday's testimony is the latest in a string of accounts to congressional committees about the attacks, which occurred September 11 and resulted in the deaths of four Americans, including U.S. Ambassador to Libya Chris Stevens.

"When you're talking about the Benghazi issue, you say, 'We positioned our forces in a way that was informed by and consistent with available threat estimates,'" McCain continued. "Then you go on to say, 'Our military was appropriately responsive,' even though seven hours passed and two Americans died at the end of that. Then you go on and say, 'We did what our posture and capabilities allowed.'"

McCain said a base in Crete was just 90 minutes away.

"We could have placed forces there," he said. "We could have had aircraft and other capabilities a short distance away at Souda Bay, Crete. So, for you to testify before this committee that they were consistent with available threat estimates is simply false; that our military was appropriately responsive."

"I stand by my testimony, your dispute of it notwithstanding," Dempsey replied.

McCain countered, "Well, perhaps you can give me some facts that would substantiate it."

Dempsey then said that a contingent was not sent because the State Department didn't request one.

"So it's the State Department's fault," McCain challenged.

"I'm not blaming the State Department," Dempsey responded. "I'm sure they had their own assessment."

Dempsey said he stood by the conclusion of an independent review board, which concluded the "interagency response was timely and appropriate, but there simply was not enough time, given the speed of the attacks, for armed U.S. military assets to have made a difference."

The board has made 29 recommendations, all of which have been accepted by the State Department.

Later in his testimony, Dempsey told Sen. Angus King, I-Maine, that the bases in the Mediterranean have aircraft, which "wasn't the right tool for the particular threat we faced."

Dempsey noted that, at the time, he was also concerned with other potential flashpoints -- Sanaa, Yemen; Khartoum, Sudan; Islamabad and Peshawar, Pakistan; Kabul, Afghanistan; and Baghdad, Iraq. "We had some pretty significant intel threat streams against those places as well," he said.

But McCain said he had seen the threat estimates "and none of them rose to the level of the threat in Benghazi ... that they could not withstand a sustained attack."

In response to a question from Sen. Kelly Ayotte, R-New Hampshire, Defense Secretary Leon Panetta said he was aware of a cable sent in August by Ambassador Stevens that said security in Benghazi was not adequate.

"Unfortunately, there was no specific intelligence or indications of an imminent attack on that -- U.S. facilities in Benghazi," Panetta said. "And frankly without an adequate warning, there was not enough time given the speed of the attack for armed military assets to respond."

He also noted that the National Counterterrorism Center had identified some 281 threats to U.S. diplomats, diplomatic facilities, embassies, ambassadors and consulates during the six months before the attack in Benghazi.

"And to deal with that, I mean, that's not our responsibility," he said. "That's the State Department's responsibility."