Poll: Iran Biggest Threat to U.S.

Americans' fears about Iran have grown sharply over the last few months as efforts by the United States and Europe to slow Tehran's nuclear program have been firmly rejected, a poll found.

More people in this country now rate Iran as the biggest threat to the U.S., 27 percent, than say that about any other country, including North Korea, China and Iraq, according to the Pew Research Center for the People & the Press.

As recently as October, Iraq and China were seen as the biggest threats, closely followed by North Korea.

"The threat from Iran has really penetrated, with two of three saying Iran's nuclear program represents a major threat," said Andrew Kohut, director of the Pew Research Center. "Among people who have been following news about the issue, there's even greater concern."

Two-thirds or more of those polled said they think that if Iran develops nuclear weapons, it is likely to attack Israel, Europe or the United States. Even more, 82 percent, say it's likely that a nuclear-armed Iran would provide nuclear weapons to terrorists.

More than three-fourths say the United Nations should take the lead in dealing with Iran on the nuclear issue, while 17 percent said the U.S. should take the lead role.