President Obama calls for dismantling IS 'network of death' at UN General Assembly

United Nations: President Obama told the United Nations amid a U.S.-led bombing campaign against Islamic State militants that he will build a coalition to "dismantle this network of death."

Obama told the assembled leaders on Wednesday that the "only language understood by killers like this is the language of force."

In remarks prepared for delivery, the president warned those who have joined the Islamic State to "leave the battlefield while they can."

After weeks of launching strikes against militant targets in Iraq, Obama extended the military action into Syria on Monday. The U.S. was joined by a coalition of five Arab nations.

President Obama denounced Russian aggression in Europe at the UN General Assembly on Wednesday, but said Washington would lift sanctions if Moscow changes course.

"Russian aggression in Europe recalls the days when large nations trampled small ones in pursuit of territorial ambition," Obama said, adding that a recent ceasefire agreement in Ukraine offers an opening towards diplomacy and peace.

"If Russia takes that path — a path that for stretches of the post-Cold War period resulted in prosperity for the Russian people — then we will lift our sanctions and welcome Russia's role in addressing common challenges."

President Obama also acknowledged that the United States had its own racial and ethnic tensions during a speech at the United Nations focused on world conflicts.

"Yes, we have our own racial and ethnic tensions. And like every country, we continually wrestle with how to reconcile the vast changes wrought by globalization and greater diversity with the traditions that we hold dear," he said.