(CBS) President Obama called on the U.N. Security Council to pass a resolution ensuring that Syria's chemical weapons stockpile is destroyed in accordance with an international ban, but is insisting that any such diplomatic agreement be backed by "consequences" if Syrian President Bashar Assad does not comply.
Speaking before the United Nations General Assembly Tuesday morning, the president warned that a failure to do so "will show that the U.N. is incapable of enforcing the most basic of international laws."
On America's other key international challenges in the region, including Iran's nuclear program and peace talks between Israelis and Palestinians, Mr. Obama indicated he will continue to pursue diplomatic solutions and engage in the region.
Mr. Obama "made the point that some of the current pressing conflicts - Syria, Iran, the Middle East - are a test for the U.N., which has lost credibility, and has failed, in recent years," reports CBS News' Pamela Falk, from the U.N.
"By talking about the founding definition of the role of the U.N. - to prevent between states, not slaughter within states - President Obama was explaining to the American public and to the 200 world leaders gathered, that the U.S. may have to act, if the U.N. fails," Falk said.
The conflict in Syria demands a more robust response from the international community, the president said, noting that the response "has not matched the scale of the challenge." A Security Council resolution would be a "bare minimum."
Mr. Obama reiterated that America was still prepared to use military force to protect its interests, but said diplomatic solution is the preferred path forward as long as it is backed by a credible military threat.
Though the U.S. is working with Russia and other allies to negotiate an agreement to place Syria's weapons under international control and destroy them, Mr. Obama also took aim at Russian President Vladimir Putin's suggestion that Assad's regime was not responsible for an August 21 chemical weapons attack.
"It is an insult to human reason - and to the legitimacy of this institution - to suggest that anyone other than the regime carried out this attack," he said.
The president also pledged an additional $340 million in humanitarian aid for the country.
In addition to Syria, the president's speech was being closely watched for any sign of U.S. engagement with Iran over the country's nuclear development. By the time of his speech Tuesday morning, Mr. Obama's words had become almost secondary to the question of whether he would meet Iranian President Hasan Rouhani face to face, perhaps in an unscheduled run-in in the hallways of the United Nations.
A meeting between the two, however, never materialized. Senior administration officials clarified that a formal bilateral meeting was never on the table.
"We indicated that the two leaders could have had a discussion on the margins if the opportunity presented itself," a senior administration official said. However, the official added, "The Iranians got back to us; it was clear that it was too complicated for them to do that at this time given their own dynamic back home."
The leaders of the U.S. and Iran have not met face to face since before the 1979 Islamic Revolution in Iran, but recent statements by Rouhani, who is more moderate than his predecessor, Mahmoud Ahmadinejad, have taken a more conciliatory tone that suggest a possible opening for diplomatic relations. Mr. Obama and Rouhani have also exchanged letters.
The U.S. has long sought to limit Iran's uranium enrichment out of suspicion the country is trying to produce a nuclear weapon. Iranian leaders, however, have insisted they are only seeking to produce nuclear energy.
Secretary of State John Kerry and Mohammad Zarif, Iran's new foreign minister and chief nuclear negotiator, are set to meet later this week with other foreign ministers involved in international talks about Iran's nuclear program. Mr. Obama indicated in his speech that he would be directing Kerry to pursue an agreement with Iran about the country's nuclear program in coordination with the European Union, the United Kingdom, France, Germany, Russia and China.
"We should be able to achieve a resolution that respects the rights of the Iranian people, while giving the world confidence that the Iranian program is peaceful. To succeed, conciliatory words will have to be matched by actions that are transparent and verifiable," the president said. While he said a diplomatic solution was preferable, Mr. Obama reiterated that the U.S. will not allow Iran to develop a nuclear weapon.
In addition to Iran and Syria, Mr. Obama indicated he will spend much of his remaining time in office on a two-state solution to the Israeli-Palestinian conflict. He outlined steps taken by both sides to restart negotiations on issues like borders, security, refugees and Jerusalem, and said the time was "ripe" for the international community to back talks in the region. The peace talks will be on the agenda when Mr. Obama meets with Israeli Prime Minister Benjamin Netanyahu at the White House next Monday.
"Real breakthroughs on these two issues - Iran's nuclear program, and Israeli-Palestinian peace - would have a profound and positive impact on the entire Middle East and North Africa," Mr. Obama said.
Much of Mr. Obama's lengthy address was aimed at defining America's changing role in the world and the Middle East as it moves away from the war footing of the last decade. Among the changes he outlined were more limits on the use of drones, working to close the prison at Guantanamo Bay, and reviewing practices around the collection of intelligence "so as to properly balance the legitimate security concerns of our citizens and allies, with the privacy concerns that all people share."
And while he shied away from the nation-building of the George W. Bush years, Mr. Obama made it clear that he believes America must play an active role on the world stage
"The danger for the world is that the United States, after a decade of war; rightly concerned about issues back home; and aware of the hostility that our engagement in the region has engendered throughout the Muslim World, may disengage, creating a vacuum of leadership that no other nation is ready to fill," he said. "I believe that would be a mistake. I believe America must remain engaged for our own security. I believe the world is better for it. Some may disagree, but I believe that America is exceptional - in part because we have shown a willingness, through the sacrifice of blood and treasure, to stand up not only for our own narrow self-interest, but for the interests of all."
Rouhani is scheduled to address the assembly Tuesday afternoon. Mr. Obama has scheduled meetings with Lebanese president Michel Suleiman and Palestinian President Mahmoud Abbas.
© 2013 CBS Interactive Inc. All Rights Reserved.