Israeli Defense Minister Ehud Barak lashed out at his critics on Thursday, saying that the decision on how to counter the threat of a nuclear-armed Iran lies within the exclusive domain of the government.

"The prime minister, defense minister and foreign minister hold responsibility. A decision (to attack Iran), once one is needed, will be made by the government of Israel, not by groups of citizens or editorials," Barak said at a Knesset (parliament) session to swear-in a new home front defense minister.

The remark came against a backdrop of heated deliberations within the government, public and media in recent days over a possible military strike on Iran, and reports of deepening rifts with the United States over its timing if sanctions and diplomacy fail in coercing Tehran to end what many in the West contend is a clandestine nuclear weaponization program.

In a highly unusual public comment, Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff, cautioned at a Pentagon briefing on Tuesday that an Israeli strike would fail to destroy Iran's nuclear program, only temporarily set it back.

"I may not know about all of their capabilities, but I think that it's a fair characterization to say that they could delay but not destroy Iran's nuclear capabilities," he said.

U.S. Defense Secretary Leon Panetta, who two weeks ago visited Israel for high-level discussions, was also on hand to brief reporters, saying that he did not believe that Israel had made a decision on whether to attack Iran at the present time. He reiterated Washington's position that there was still time for harsher sanctions and negotiations to run their course.

On Thursday, however, Barak again expressed urgency about responding to Tehran's accelerated efforts to acquire a nuclear weapon.

"Dealing with a nuclear Iran in the future will be immeasurably more complex, dangerous and costly -- in lives and resources," said Barak, alluding to the advantages of a possible pre-emptive military strike.

Noting his years of experience in top positions in several governments, including as prime minister, Barak said that no issue in the past generation has been discussed within the government " as deeply and with greater transparency" than Iran's nuclear program.