UNITED NATIONS >> Declaring the world at a crossroads between war and peace, President Barack Obama vowed at the U.N. on Wednesday to lead a coalition to dismantle an Islamic State “network of death” that has wreaked havoc in the Middle East and drawn the U.S. back into military action.

Speaking to the annual gathering of the United Nations General Assembly, Obama said the U.S. would be a “respectful and constructive partner” in confronting the militants through force. But he also implored Muslims in the Middle East to reject the ideology that has spawned groups like the Islamic State and to cut off funding that has allowed that terror group and others to thrive.

“Ultimately, the task of rejecting sectarianism and extremism is a generational task — a task for the people of the Middle East themselves,” Obama said in his 38-minute address. “No external power can bring about a transformation of hearts and minds.”

Later, the president convened an unusual meeting of the U.N. Security Council, during which members unanimously adopted a resolution requiring all countries to work to prevent the recruitment and transport of would-be foreign fighters preparing to join terrorist groups such as the Islamic State group.

Obama’s address came against the backdrop of an expanded U.S. military campaign against the Islamic State group, with airstrikes now hitting targets in both Iraq and Syria. A coalition of five Arab nations joined the U.S. this week in the strikes in Syria: Bahrain, Jordan, Saudi Arabia, United Arab Emirates and Qatar.

The U.S. also opened another military front with airstrikes this week against a new al-Qaida cell that the Pentagon said was “nearing the execution phase” of a direct attack on the U.S. or Europe.

The threats have drawn Obama back into conflicts in the Middle East that he has long sought to avoid, particularly in Syria, which is mired in a bloody three-year civil war. Just months ago, the president appeared to be on track to fulfill his pledge to end the U.S.-led wars he inherited in Iraq and Afghanistan.

Obama sought to distinguish this current military campaign from those lengthy wars, declaring that he has no intention of sending U.S. troops to occupy foreign lands.

The militant threat in the Middle East is just one in a series of global crises that have tested Obama this year. Russia has repeatedly flouted warning from the U.S. and Europe to stop its threatening moves in Ukraine. And leaders in West Africa have criticized Obama for not doing more to help combat an Ebola outbreak that is believed to have infected more than 5,800 people in Liberia, Sierra Leone, Guinea, Nigeria and Senegal.

Obama took on Russia directly in his remarks, accusing Moscow of sending arms to pro-Kremlin separatists, refusing to allow access to the site of a downed civilian airliner and then moving its own troops across the border with Ukraine.

“This is a vision of the world in which might makes right, a world in which one nation’s borders can be redrawn by another, and civilized people are not allowed to recover the remains of their loved ones because of the truth that might be revealed,” Obama said. “America stands for something different.”

Still, Obama held open the prospect of a resolution to the monthslong conflict between Russia and Ukraine. While he has previously expressed skepticism about a fragile cease-fire signed earlier this month, he said Wednesday that the agreement “offers an opening” for peace.

If Russia follows through on the agreement, Obama said the U.S. will lift economic sanctions that have damaged Russia’s economy but so far done little to shift President Vladimir Putin’s approach.

As Obama spoke, Russian Foreign Minister Sergei Lavrov sat in the audience at the U.N., staring down at a stack of papers without glancing up at Obama.

The chaotic global landscape Obama described Wednesday stood in contrast to his remarks at the U.N. one year ago, when he spoke of diplomatic openings on multiple fronts. At the time, the U.S. was embarking on another attempt to forge an elusive peace between Israelis and Palestinians and there were signs of a thaw in the decades-old tensions between the U.S. and Iran.

The Mideast peace talks have since collapsed, though the president said Wednesday that “as bleak as the landscape appears, America will never give up the pursuit of peace.” And while the U.S., Iran and world powers are now in the midst of nuclear negotiations, the talks are deadlocked and there is skepticism about whether a deal can be reached by a Nov. 24 deadline.

“My message to Iran’s leaders and people is simple: Do not let this opportunity pass,” Obama said. “We can reach a solution that meets your energy needs while assuring the world that your program is peaceful.”

Later Wednesday, Obama held his first one-on-one meeting with new Iraqi Prime Minister Haider al-Abadi, who took office this month. The U.S. has blamed the former Iraqi leadership’s lack of inclusiveness for giving the Islamic State a recruiting tool and had made the formation of a new government a condition for deeper military action to stop the militant group.

Obama praised al-Abadi as “the right person to help work with a broad-based coalition of Iraqis,” and he said the U.S. supports the new prime minister’s “political vision.”

Even as the president cast the U.S. as the main driver of peace and security around the world, he acknowledged that his country has not always lived up to its own ideals. He singled out in particular the recent clashes between police and protesters in Ferguson, Missouri, that followed the shooting death of a black teenager.

“Yes, we have our own racial and ethnic tensions,” Obama said. “But we welcome the scrutiny of the world. Because what you see in America is a country that has steadily worked to address our problems and make our union more perfect.”