An Iranian nuclear strike on the United States could be more devastating than the Japanese attack in 1941, Gingrich told Project Israel, a non-profit organization established to provide the American media with information on Israel.
On Thursday Project Israel held a press conference on the Iranian threat, and invited presidential hopefuls to participate and voice their opinions on the issue.
"The stakes for Israel are even graver," Gingrich said. "The use of one or more nuclear weapons against Israel would constitute a second
Gingrich emphasized the gravity of the Iranian threat in his statement: "Indeed, the Iranian President does not even require us to read a book like Mein Kampf to understand how serious he is. He enthusiastically makes speeches proclaiming to the world his commitment to genocidal annihilation of another nation."
"Meanwhile the civilized world wrings its hands and the United Nations acts with contemptible weakness," he added.
Rival Democratic candidate Senator Hillary Clinton issued a statement noting that American policy on Iran must be "clear, unambiguous and effective."
The US cannot let Iran build or acquire nuclear weapons, nor support terrorism, she said.
The senator responded firmly to Iranian President Mahmoud Ahmadinejad's statement that Israel should be "wiped off the map," saying, "We must not tolerate threats to the existence of Israel."
The leading Democratic candidates told Project Israel that Iran can be prevented from acquiring nuclear weapons through economic and diplomatic channels.
Democratic Senator Barack Obama, Clinton's chief Democratic rival, declared that, "Allowing Iran - a radical theocracy that supports terrorism openly threatens its neighbors - to acquire nuclear weapons is a risk we cannot take."
Obama demanded the UN take stronger action and boost sanctions on Tehran. "All nations need to understand that, while Iran's most explicit an intolerable threats are aimed at Israel, its conduct threatens all of us," Obama said.
Democratic candidates John Edwards, Joe Biden and Christopher Dodd also said sanctions on Ahmadinejad's regime should be boosted.