Two of the nation's most high-profile Democratic candidates for Senate seats have parted ways over U.S. policy on Iran, which is a top national security issue this election year.

Bob Kerrey, a former U.S. Navy SEAL and two-term senator from Nebraska who is running to win back his former seat, released an ad on Tuesday strongly opposing an attack on Iran, which he said would be "a disaster."

Meanwhile, Elizabeth Warren, a Democratic Senate hopeful in Massachusetts, came under fire for a hawkish statement on Iran that contradicts intelligence assertions by senior U.S. defense officials.

Warren's campaign website features a policy statement declaring that "Iran is pursuing nuclear weapons" and "Iran’s pursuit of nuclear weapons is unacceptable because a nuclear Iran would be a threat to the United States, our allies, the region, and the world."

The statement continues, "The United States must take the necessary steps to prevent Iran from acquiring a nuclear weapon. I support strong sanctions against Iran and believe that the United States must also continue to take a leadership role in pushing other countries to implement strong sanctions as well. Iran must not have an escape hatch."

Warren's claim that "Iran is pursuing nuclear weapons" is especially notable because it contradicts public statements by Defense Secretary Leon Panetta as well as reported intelligence findings of the U.S. and Israeli governments.

At a February hearing, Panetta told lawmakers, "The intelligence does not show that [Iran officials] have made the decision to proceed with developing a nuclear weapon."

Reuters reported in March, "The United States, European allies and even Israel generally agree on three things about Iran's nuclear program: Tehran does not have a bomb, has not decided to build one, and is probably years away from having a deliverable nuclear warhead."

An activist-blogger who goes by the pseudonym Vast Left-Wing Conspiracy said he questioned Warren about the statement at a public appearance in Somerville, Mass., on Sunday. The blogger wrote:

I asked why her stand is that Iran is pursuing nuclear weapons ... Warren said she thinks the data says they are working on nuclear weapons. I repeated that, no, even the administration says there's no evidence of that. She said she'd look into it, saying it's important that political statements not ... add fuel to the fire.

Salon's Glenn Greenwald tweeted about the blogger's interview, calling it "constructive."

When reached by The Huffington Post on Tuesday, a representative of the Warren campaign did not immediately provide a comment.

In contrast, Tuesday's campaign ad by Kerrey presents a harsher condemnation of a possible future Iran invasion than perhaps any made by a sitting member of Congress.

"Three trillion dollars for Afghanistan and Iraq," Kerrey says in the spot. "Six thousand Americans dead. I don't know what the numbers are that are disabled with all kinds of injuries. There's 80 million people living in Iran. I mean, if we were undersized with 250,000 men and women going into Iraq, it's going to take a million to go to war with Iran."

"It would be a disaster," he concludes. "It'll make Iraq and Afghanistan look like a cakewalk."

Awarded a Medal of Honor and a Bronze Star for his service as a U.S. Navy SEAL in Vietnam from 1966 to 1969, Kerrey had his military activities put under the spotlight in 2001. News reports detailed a Swift Boat raid that he had led on a peasant village in Vietnam that resulted in the death of a dozen or more civilians, including women and young children, according to participants in the raid.

Kerrey has said he did not personally participate in the killings but accepted responsibility for the actions of his SEAL team, expressing great remorse. "You can never, can never get away from it. It darkens your day. I thought dying for your country was the worst thing that could happen to you, and I don't think it is. I think killing for your country can be a lot worse."