Republican presidential candidate and Kentucky Sen. Rand Paul says he supports military action against Iran to prevent them from getting a nuclear weapon, even though he says it would only delay Iran getting a bomb.

"I think military force always has to back up diplomacy," Paul told radio host Mark Levin on Tuesday. "Diplomacy doesn't work without military force behind it, and I think making that decision is a difficult decision, but ultimately yes you have to have military force that backs up the diplomatic negotiations that you have. We have to say that there has to be force as a backdrop to this."

Paul told Levin he believed any decision made on Iran has to have "the best outcome" in mind. Paul said he thought an attack on Iran might delay them developing a nuclear weapon, but would actually allow them to develop a bomb faster in the long run.

"The decision has to be made, which is the best way to try have, you know, an outcome that is the best outcome. And I think the best outcome -- if you were looking at the best outcome from there -- if we were to use military force I think we delay a nuclear weaponization but I think ultimately what you end up having is you have situation where there are no more inspections and there may well be a quicker development of a nuclear weapon after that," Paul stated.

"I think as long as we have a chance of negotiations we should continue it, but it has to be verifiable. I think the mistake that this president has made is that I think he was so eager for a deal that he cut a deal that I think allows the collapse of the sanctions before you have evidence of consistent compliance."

Paul's willingness to use military force against Iran is markedly different from his past positions -- as a surrogate for his dad in 2007 and 2008, Paul said Iran didn't pose a threat to our national security.

"I find it hard to believe that a country that can't refine their gas is somehow a threat to our national security," Paul said at a 2008 campaign event for his father in Montana. In one 2007 interview with radio host and conspiracy theorist Alex Jones, Paul said that Iran wasn't a threat to the U.S. or Israel, citing estimates that Israel already has 100 nuclear weapons.