Updated at 2:05 p.m. ET
(CBS/AP) UNITED NATIONS - Israeli Prime Minister Benjamin Netanyahu is making his case against Iran before the United Nations General Assembly, arguing that time is quickly running out to stop the Islamic Republic from becoming a nuclear power and the threat of force must be seriously considered.
"At this late hour, there is only one way to peacefully prevent Iran from getting atomic bombs, and that is by placing a clear red line on Iran's nuclear weapons program," Netanyahu said.
His demand that President Obama declare red lines that would trigger an American attack on Iran's nuclear facilities has been rejected in Washington and sparked a public rift between the two leaders.
But Netanyahu said at U.N. headquarters Thursday that nothing could imperil the world more than a nuclear-armed Iran.
"To understand what the world would be like with a nuclear-armed Iran, just imagine a world with a nuclear-armed al Qaeda," Netanyahu said.
At the beginning of his address Thursday, he disputed Iranian leader Mahmoud Ahmadinejad's statement from earlier in the week that Israel has "no roots" in the Middle East. Netanyahu told the gathered world leaders and diplomats: "The Jewish people have come home. We will never be uprooted again."
During his three-day visit, Netanyahu is scheduled to meet with U.N. Secretary-General Ban Ki-Moon, EU foreign policy chief Catherine Ashton, Canadian Prime Minister Stephen Harper who recently expelled the Iranian ambassador from his country and U.S. Secretary of State Hillary Clinton. He is not scheduled to meet Mr. Obama; however, the White House said Thursday Mr. Obama would have a follow-up call with Netanyahu Friday.
While Israel is convinced that Iran is pursuing a nuclear weapon, American officials believe Iran has not yet made a final decision to take the plunge, even as it develops much of the infrastructure needed to do so.
Mr. Obama has repeatedly said he will not allow Iran to gain nuclear weapons and has said the U.S. would be prepared to use force as a last resort. But in an interview Sunday with CBS' "60 Minutes" he also vowed to "block out any noise that's out there" on the issue, in an apparent swipe at Netanyahu.
(Below, watch Part 1 of Mr. Obama's interview with Steve Kroft)
Netanyahu claims international diplomatic efforts and economic sanctions have failed, but a new report from the Israeli Foreign Ministry, leaked Thursday, concludes that sanctions are hitting Iran hard. According to the report, details of which appeared in the Haaretz newspaper, Iran's oil exports declined by over 50 percent in the past year and sanctions on Iran's central bank have made it difficult for the regime to access its foreign currency.
An Israeli official confirmed the new report but refused to elaborate on it. The official spoke on condition of anonymity because he was not authorized to discuss internal government documents.
The Obama administration has urgently sought to hold off Israeli military action, which would likely result in the U.S. being pulled into a conflict and cause region-wide mayhem on the eve of American elections.
Such an attack would almost certainly lead to retaliatory Iranian missile strikes on Israeli population centers. On Sunday, Iranian leaders suggested they may strike Israeli preemptively if they feel threatened.
Israel considers a nuclear-armed Iran to be an existential threat, citing Iranian calls for Israel's destruction, Iran's development of missiles capable of striking the Jewish state and its support for hostile Arab militant groups.
Also Thursday, on the sidelines of the General Assembly, key figures will gather for a Friends of Yemen meeting that will be co-chaired by British Foreign Secretary William Hague, Yemen's President Abed Rabbo Mansour Hadi and Saudi Arabia's Deputy Foreign Ministe Abdulaziz bin Abdullah Abdullah. The meeting will produce a communique aimed at generating support for Hadi, who took office in February after more than a year of political turmoil and is now trying to steer his country's democratic transition.
Later, political directors from the United States, Russia, China, Britain, France and Germany will be meeting on the Iranian nuclear issue.
A few hours before Netanyahu flew to the U.S., Ahmadinejad, known for past fiery denunciations of the United States and Israel, spoke at length about his vision for a "new world order" during his speech at the U.N. His speech on Wednesday happened to fall on Yom Kippur, the most sacred day on the Jewish calendar, devoted to fasting, prayer and introspection.
(Watch at left)
"We say that occupation should be done away with," said Ahmadinejad. "Warlike behavior should be done away with. Terrorism should be done away with. The killing of women and children should be done away with. Has the Zionist regime done anything other than this during the last 65 years? No, they haven't."
Netanyahu has said he is going to the U.N. to draw attention to what Israel perceives as the Iranian threat. Speaking to his Cabinet on Sunday, he said at the U.N. he would "reiterate that the most dangerous country in the world must not be allowed to arm itself with the most dangerous weapon in the world." He did not elaborate.
On Tuesday, the Maariv daily reported that Netanyahu would spell out what limits the international community should set for Iran to prevent it from becoming a nuclear power and how long that will take. Netanyahu has never laid out these limits precisely.
Iran insists its nuclear program is for peaceful purposes but Israel, the U.S. and other Western allies reject the claim. Four rounds of U.N. sanctions have already been placed on Iran.
A U.N. report last month only reinforced Israeli fears, finding that Iran has moved more of its uranium enrichment activities into fortified bunkers deep underground where they are impervious to air attack. Enrichment is a key activity in building a bomb, though it has other uses as well, such as producing medical isotopes.
Israel's timeline for military action is shorter than that of the United States, which has far more powerful bunker-busting bombs at its disposal, and there is great suspicion in Israel over whether in the moment of truth Mr. Obama will follow through on his pledge.
Netanyahu has a history of fiery speeches at the U.N. General Assembly.
In 2009, he waved the blueprints for the Nazi death camp Aushwitz and invoked the memory of his own family members murdered by the Nazis while making his case against Iran's Holocaust denial and threats to destroy Israel.
To those who remained at the General Assembly while Iranian President Mahmoud Ahmadinejad spoke, he chastised: "Have you no shame? Have you no decency?"
And last year, he warned the world about the threat of militant Islam and Iran.