A nuclear-armed Iran is intolerable not only to the United States, but also to the entire international community, said Robert Joseph, undersecretary of state for arms control and international security, at a briefing on Wednesday.

"With nuclear weapons, Teheran would be even more aggressive in its support for terror and its subversion of peace and stability in Lebanon, in Iraq, in Afghanistan, and elsewhere in the region," Joseph said.

"Teheran could light a fuse for further nuclear proliferation by those countries that would be threatened by Iran, bringing into question the effectiveness and, in fact, the future of the Nuclear Nonproliferation Regime," Joseph said.

Nonetheless, Joseph said that the United States is continuing to pursue a diplomatic approach to "stopping Iran's pursuit of nuclear weapons."

The United States has accused Iran of trying to develop nuclear weapons under the cover of civilian nuclear programs. Iran has said that its nuclear programs are for peaceful purposes only.

The United Sates is now seeking to impose sanctions on Iran for its refusal to comply with a UN Security Council resolution demanding Teheran stop uranium enrichment.