Panellists (left to right) U.S. Senator Mark Udall, Norm Ornstein of the American Enterprise Institute and Senator Lindsey Graham discuss security issues at an international conference in Halifax on Saturday. (Andrew Vaughan/The Canadian Press)

A U.S. lawmaker sent ripples through an international conference in Halifax on Saturday by saying his country should be prepared to launch a military attack on Iran that would "neuter" the hardline regime.

Republican Senator Lindsey Graham of South Carolina said his party would support military action against Iran that would destroy its ability to fight back while allowing its people to rise up.

But Canadian Defence Minister Peter MacKay, the host of the conference, said that a military attack on Iran would have negative fallout and that international sanctions are preferable.

Graham surprised attendees at the Halifax International Security Forum with his hawkish rhetoric, saying an attack could cripple Iran's nuclear program as well as its armed forces.

The U.S. and its Western allies, including Canada, believe Iran is trying to develop a nuclear weapon. Tehran maintains it is peacefully pursuing nuclear power to meet its energy needs.

'Sink their navy, destroy their air force and deliver a decisive blow to the Revolutionary Guard.'— Lindsey Graham, U.S. Republican senator

Graham noted that international sanctions are beginning to work on Iran, but said U.S. President Barack Obama should make it "abundantly clear" all options are on the table.

"So my view of military force would be not to just neutralize their nuclear program, which are probably dispersed and hardened, but to sink their navy, destroy their air force and deliver a decisive blow to the Revolutionary Guard," Graham told a panel.

"In other words, neuter that regime."

Graham said the last thing his country needs is another war, but the last thing the world needs is a nuclear-armed Iran.

Asked about Graham's tough proposal, MacKay told a later panel that Canada was not pursuing such an aggressive approach.

"No question there would be a negative reaction to that course of action, although I know that has perhaps provoked some of the hottest discussions in the hallways," the MP for Central Nova said.

MacKay said collective international sanctions can be used to fight Iran and change the country's thinking. He said sanctions are aimed at the regime, not its people.

Graham created the biggest buzz at the second annual security conference that MacKay is hosting in his home province. Graham serves on six senate committees, including armed services, homeland security and veterans affairs. He also a member of the air force reserves.

"Nobody would like to see the sanctions work any more than I would because I'm still in the military and I get to meet these young men and women on a regular basis and I know what it's been like for the last nine years," he told an audience of foreign politicians, diplomats and academics.

"And if you use military force, if sanctions are not going to work, and a year from now it's pretty clear they're not going to work, what do our friends in Israel do?"

Israel 'still in the stage of diplomacy'

Israeli Defence Minister Ehud Barak said "we are still in the stage of diplomacy and sanctions" but Iran remains a threat.

"Based on experience and looking at the example they're using, which is probably the North Korean example, you can easily see the basic objective is to defy, defeat and deter the whole world," Barak said.

"I will be happy … to end up finding myself wrong, based on future developments, but I wonder whether this is the case."

Another U.S. senator, Democrat Mark Udall, said he wasn't willing to completely support Graham because what he was advocating would have "worldwide repercussions."

"I'm not willing to put my support behind that step here in a theoretical context, but I think you've got to keep every option on the table and let the Iranian regime know that we're deadly serious, not just as the United States of America, but as a world community," Udall told Graham and his fellow panellists.