"I don't want to saber rattle, but I wouldn't take anything off the table," said Senator Joe Lieberman, who made an unsuccessful run for the Democratic presidential nomination this year.

Lieberman added that the use of force should be a last resort, and expressed hope that a consistent US-European diplomatic approach "will make that never even a topic of actively serious consideration."

But he told defense reporters Iran "is on a path to develop a very significant nuclear weapons program" and is working hard to develop missiles with ranges capable of striking targets in Europe as well as the Middle East.

"If it were up to me, I would try to get the United States in direct communication with the Iranian leadership but on a very tough, tough basis -- let's decide what the future is going to be," he told defense reporters here.

"You have to marshall diplomatic support with the UN, but in the end they've got to feel we're really serious about this for them to stop the development of nuclear weapons, which in my opinion they are on a headlong course to develop," he said.

Iran's clerical regime insists its nuclear program is for peaceful purposes, and that it does not seek to develop nuclear weapons.

Defying UN pressure, President Mohammad Khatami has said Iran will not give up uranium enrichment efforts, which could be used to produce bomb-making material.

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