President Obama phoned Russian President Vladimir Putin on Monday to discuss a ceasefire agreement in Syria, the White House said.
After weeks of talks, the U.S. and Russia agreed to a ceasefire in the Middle Eastern nation, which has been torn apart for five years by civil war.
“We recognize … that this is going to be difficult to implement," said Earnest. "We know that there are a lot of obstacles and there are sure to be some setbacks. But this is a moment of opportunity.”
Under the agreement, which is set to take effect Saturday, Russian and Assad’s forces would agree to stop airstrikes against opposition fighters who are verified by both the U.S. and Russia to be party to the pact.
Both sides would also agree to stop efforts to take territory and only use force in self-defense.
The Syrian regime and opposition groups have until midday Friday to agree to the pact, which is designed to bring an end to the civil war and ensure that humanitarian aid is delivered to millions of displaced civilians.
The agreement does not apply to strikes against Islamic State in Iraq and Syria (ISIS), al Qaeda’s affiliate in Syria (known as al Nusra) or any other United Nations-designated terrorist group.
The cessation of hostilities will be enforced by a United Nations task force. A previous ceasefire agreement broke down earlier this month when Russian forces continued to bomb rebel-held strongholds in northern Syria.