VIDEO - There is no doubt that Iran's nuclear program is an attempt by the Islamic Republic to gain military nuclear weapons, and the United States will not allow Tehran to go nuclear, the US Under-Secretary of State for Political Affairs, Ambassador Nicholas Burns, said during the Herzliya Conference Sunday evening.

"Iran is seeking a nuclear weapon, there's no doubt about it," Burns said, adding: "There's no debate among experts. It's seeking a nuclear weapon at its plant at Nantz."

Watch live broadcast of Herzliya Conference

The US under-secretary added that his country "is not seeking, at all, a confrontation with Iran," but said that "the policy of the United States is that we cannot allow Iran to become a nuclear weapons state." His declaration was met with applause among the delegates attending the conference.

"The US has not gone out to look for an argument with Iran," Burns emphasized, but Iran has refused to back down in its attempt to destabilize the region, prompting the US to station "two battle groups in the Persian gulf," and to target Iranian networks enabling attacks on US soldiers in Iraq. "We have an absolute right to defend our soldiers," he added. .

Burns outlined a series of diplomatic steps taken by Washington against Iran, and urged the countries of the European Union to end their economic cooperation with the Islamic Republic.

'2007 year of decision'

He also highlighted Iran's divisive role in the Middle East, support of Palestinian terror groups, Hizbullah, and attempt to topple the government of Lebanese Prime Minister Fouad Siniora.

"In Lebanon, in a couple days time, President Chirac will host a conference, so that the democratic nations stand up in the world against Hizbullah, against those who want to destabilize the democratic government of Siniora," Burns said, adding that the US will help this effort.

"We're all going to defend a democratically elected government from that axis…and we're going to help democracy survive and hopefully prosper," he said. Burns expressed hope that Iran would return to the negotiating table, and said the offer for negotiations was still open.

He affirmed Washington's close alliance with Jerusalem, saying: "We are committed to our alliance with Israel. We are committed to being Israel's strongest security partner. I can't remember a time when the relationship between our two countries was stronger than it is today."

Transportation Minister and former defense minister Shaul Mofaz, who had met with Burns before their joint appearance at the Herzliya conference, said the coming year would be a crucial time for deciding the future of the Middle East.

"The year of 2007 is a year of decisiveness," Mofaz said. "Iran of 2007 has all the components to threaten us existentially, and the whole of the region."

"Mahmoud Ahmadinejad believes he is on a divine mission. I'm the last person to call him insane," Mofaz said. "Although I am not qualified as a psychologist, it's clear to me we are dealing with a person driven by an extremist ideology, who is determined to fulfill his mission," he added.

"Iran is the heart of the problem in the Middle East. It is the urgent threat to the world. And it must be dealt with, before it's too late," he said, adding: "The world can't allow a situation in which a fundamentalist country - that doesn't hide its intentions - holds nuclear weapons. The free world doesn't have the privilege to drag its feet on Iran and hope for best."