UNITED NATIONS — President Barack Obama on Tuesday challenged the U.N. Security Council to hold Syria accountable if it fails to live up to pledges to dismantle its chemical weapons stockpiles. He said the United Nations’ credibility and reputation are at stake.

“If we cannot agree even on this,” Obama said, “then it will show that the United Nations is incapable of enforcing the most basic of international laws.”

The United States and Russia earlier this month brokered an agreement to secure and destroy Syria’s chemical weapons, thus averting a threatened U.S. military strike to deter and degrade Syrian President Bashar Assad’s ability to use the banned arms. Despite the agreement, Washington and Moscow remain at odds over possible consequences should Syria fail to comply.

“We believe that as a starting point the international community must enforce the ban in international weapons,” Obama said in his address to the U.N. General Assembly.

Obama also announced that the U.S. will provide $339 million in additional humanitarian aid to refugees and countries affected by the Syrian civil war, bringing the total American aid devoted to that crisis to nearly $1.4 billion. The White House said the aid will include $161 million spent inside Syria for medical care, shelter and sanitation projects, with the remainder going to help Syrian refugees in Lebanon, Jordan, Iraq, Turkey and Egypt.