President Barack Obama has challenged the international community to confront the causes of Middle East turmoil, saying the world faces "a choice between the forces that would drive us apart and the hopes we hold in common."
His speech to an annual gathering of world leaders at the UN General Assembly was his last before the November election, and campaign politics shadowed his words as he also spoke forcefully on Iran's nuclear programme, the peace prospects between Israelis and Palestinians and the tensions that can come with freedom of speech.
"I do believe that it is the obligation of all leaders, in all countries, to speak out forcefully against violence and extremism," Mr Obama said.
The president condemned the amateur anti-Muslim video made in the US that helped spark the recent protests that killed dozens of people, including the US ambassador to Libya, Chris Stevens, calling it "cruel and disgusting." But he strongly defended the US Constitution's protection of the freedom of expression, "even views that we profoundly disagree with."
Mr Obama also warned that the time to peacefully curb the Iranian nuclear crisis is running out. Iran insists its nuclear programme is peaceful, but fears that it is pursuing nuclear weapons have led Israel to threaten an attack.
Mr Obama said there is "still time and space" to resolve the issue through diplomacy, but he said that time is not unlimited. "Make no mistake: A nuclear-armed Iran is not a challenge that can be contained. It would threaten the elimination of Israel, the security of Gulf nations and the unravelling of the nuclear non-proliferation treaty," he said.
The president said the United States would never have just banned the offensive video, as some leaders in the Muslim world have advocated. "Like me, the majority of Americans are Christian, and yet we do not ban blasphemy against our most sacred beliefs," he said.
"Moreover, as president of our country and commander in chief of our military, I accept that people are going to call me awful things every day, and I will always defend their right to do so," he said, to laughter from his audience.
Running through his speech was the theme that leaders in the Muslim world also should stand up for freer speech and oppose those who vent their anger with violence.
But, he added, "Just as we cannot solve every problem in the world, the United States has not, and will not, seek to dictate the outcome of democratic transitions abroad, and we do not expect other nations to agree with us on every issue.