The White House on Sautrday announced that the United States and Russia have officially agreed on a "de-escalation zone" in southwest Syria, striking a hopeful note in efforts to end the deadly civil war in that country that has been waged for six years.

"At noon local time tomorrow, a de-escalation zone in southwest Syria will begin to take effect. Such zones are a priority for the United States, and we're encouraged by the progress made to reach this agreement," National Security Adviser H.R. McMaster said in a statement handed to reporters on Air Force One as the president returns home from the G-20 summit in Hamberg, Germany.

"After achieving this hopeful step with the governments of Russia and Jordan," McMaster said that President Trump discussed its details with multiple world leaders, including Turkish President Recep Tayyip Erdogan and German Chancellor Angela Merkel.

The Associated Press reported Friday that the U.S. and Russia had reached an agreement on a cease-fire in southwest Syria, as Trump met with Russian President Vladimir Putin. The report said this cease-fire agreement is different than the "de-escalation" zones there were being put together by Russia, Iran and Turkey.

As recently as Wednesday it was reported that de-escalation talks between Russia, Turkey and Iran had broken down, representing a setback for Russia, which is the Syrian regime's biggest supporter.

Afterwards, Secretary of State Rex Tillerson put out a statement saying the U.S. was ready to help advance these talks. "The United States is prepared to explore the possibility of establishing with Russia joint mechanisms for ensuring stability, including no-fly zones, on the ground ceasefire observers, and coordinated delivery of humanitarian assistance," Tillerson said.

The U.S. supports some rebel groups that are challenging the Bashar Assad's government in the civil war, which has killed about half a million people.

In McMaster's statement, he said that the ultimate goal of the U.S. is to end the carnage and to defeat the Islamic State, which has secured a foothold in the country.

"The United States remains committed to defeating ISIS, helping to end the conflict in Syria, reducing suffering, and enabling people to return to their homes. This agreement is an important step toward these common goals," McMaster said.