ceasefire
(Left to right) Russian Foreign Minister Sergei Lavrov, U.S. Secretary of State John Kerry and U.N. Special Envoy for Syria Staffan de Mistura attend a news conference after the International Syria Support Group meeting in Munich, Feb. 12, 2016. REUTERS/Michael Dalder

UPDATE: 1:59 p.m. EST -- The U.S. Department of State officially commented Monday in response to a tentative start date being set for a provisional agreement between the U.S. and Russia for a ceasefire in Syria. Secretary of State said in part that the halt in violence, if upheld, "will not only lead to a decline in violence, but also continue to expand the delivery of urgently needed humanitarian supplies to besieged areas and support a political transition to a government that is responsive to the desires of the Syrian people."

Kerry's full statement follows below:

I am gratified to see the final arrangements concluded today for a cessation of hostilities in Syria and call on all parties to accept and fully comply with its terms. If implemented and adhered to, this cessation will not only lead to a decline in violence, but also continue to expand the delivery of urgently needed humanitarian supplies to besieged areas and support a political transition to a government that is responsive to the desires of the Syrian people.

Today's agreement results from the committed diplomacy of many countries and groups, and I want to thank all those who worked diligently to bring it about, including the U.S. and Russian delegations and other members of the International Syria Support Group.

We are all aware of the significant challenges ahead. Over the coming days, we will be working to secure commitments from key parties that they will abide by the terms of this cessation of hostilities and further develop modalities for monitoring and enforcement.

This is a moment of promise, but the fulfillment of that promise depends on actions. All parties must meet their commitments under this agreement, ensure full implementation of UN Security Council Resolution 2254, and cease attacks on each other, including aerial bombardments. And all parties must remain committed over a period of time to make possible a political end to this conflict.

As we move forward, we will remain vigilant to ensure that implementation achieves what we set out to do, which is to stop the violence and provide the space and the opportunity for a negotiated political transition, consistent with the Geneva Communique of 2012, that unites all Syrians who reject dictatorship and terrorism and want to build a new future for their country.

Original story:

A provisional agreement between Russia and the United States to halt fighting in Syria now has an official start time, according to a BBC report Monday. A halt to fighting between the Syrian opposition, which has been supported by the U.S., and the Syrian military, which has been propped up by Russia, is tentatively scheduled to begin Saturday.

The truce, which does not include the Islamic State group or other terror organizations operating in Syria, such as the Nusra Front, would be "according to international guarantees," Syrian opposition coordinator Riad Hijab said, the Daily Star reported.

U.S. Secretary of State John Kerry and his Russian counterpart, Sergei Lavrov, reportedly had additional talks Sunday night to hammer out certain tentatively agreed-upon details of the ceasefire, which will go before U.S. President Barack Obama and Russian President Vladimir Putin for their respective approvals, according to the Ministry of Foreign Affairs of the Russian Federation.

The news comes along with a United Nations report citing war crimes as being "rampant" in Syria, leading to "a multisided proxy war steered from abroad by an intricate network of alliances," the Associated Press reported.

Kerry and Lavrov reached the provisional deal Sunday, but a potential ceasefire timeframe was not announced until Monday, according to a draft of the plan. Kerry had initially indicated that he didn't think the ceasefire would start "in the next few days."

The full text of the joint statement by the U.S. and Russia on a ceasefire in Syria follows:

The United States of America and the Russian Federation, as co-chairs of the International Syria Support Group (ISSG) and seeking to achieve a peaceful settlement of the Syrian crisis with full respect for the fundamental role of the United Nations, are fully determined to provide their strongest support to end the Syrian conflict and establish conditions for a successful Syrian-led political transition process, facilitated by the UN, in order to fully implement the Munich Statement of the ISSG on February 11th, 2016, UN Security Council Resolution 2254, the 2015 Vienna Statements and the 2012 Geneva Communiqué.

In this regard, and in furtherance of the February 11th decisions of the ISSG, the United States and Russia, as co-chairs of the ISSG and ISSG Ceasefire Task Force, announce the adoption on February 22, 2016, of the Terms for a Cessation of Hostilities in Syria attached as an Annex to this statement, and propose that the cessation of hostilities commence at 00:00 (Damascus time) on February 27, 2016. The cessation of hostilities is to be applied to those parties to the Syrian conflict that have indicated their commitment to and acceptance of its terms. Consistent with UN Security Council Resolution 2254 and the statements of the ISSG, the cessation of hostilities does not apply to “Daesh”, “Jabhat al-Nusra”, or other terrorist organizations designated by the UN Security Council.

Any party engaged in military or para-military hostilities in Syria, other than “Daesh”, “Jabhat al-Nusra”, or other terrorist organizations designated by the UN Security Council will indicate to the Russian Federation or the United States, as co-chairs of the ISSG, their commitment to and acceptance of the terms for the cessation of hostilities by no later than 12:00 (Damascus time) on February 26, 2016. In order to implement the cessation of hostilities in a manner that promotes stability and protects those parties participating in it, the Russian Federation and the United States are prepared to work together to exchange pertinent information (e.g., aggregated data that delineates territory where groups that have indicated their commitment to and acceptance of the cessation of hostilities are active, and a focal point for each side, in order to ensure effective communication) and develop procedures necessary for preventing parties participating in the cessation of hostilities from being attacked by Russian Armed Forces, the U.S.-led Counter ISIL Coalition, the Armed Forces of the Syrian government and other forces supporting them, and other parties to the cessation of hostilities. Military actions, including airstrikes, of the Armed Forces of the Syrian Arab Republic, the Russian Armed Forces, and the U.S.-led Counter ISIL Coalition will continue against ISIL, “Jabhat al-Nusra,” and other terrorist organizations designated by the UN Security Council. The Russian Federation and United States will also work together, and with other members of the Ceasefire Task Force, as appropriate and pursuant to the ISSG decision of February 11, 2016, to delineate the territory held by "Daesh," "Jabhat al-Nusra" and other terrorist organizations designated by the UN Security Council, which are excluded from the cessation of hostilities.

In order to promote the effective implementation of the cessation of hostilities, the ISSG Ceasefire Task Force, co-chaired by the United States and Russia, has been established under UN auspices, including political and military officials from the co-chairs and other Task Force members; the UN Office of the Special Envoy for Syria (OSE) serves as secretariat. The primary functions of the Task Force are, as provided in the ISSG Statement of February 11, to: a) delineate the territory held by “Daesh”, “Jabhat-al-Nusra” and other terrorist organizations designated by the United Nations Security Council; b) ensure communications among all parties to promote compliance and rapidly de-escalate tensions; c) resolve allegations of non-compliance; and d) refer persistent non-compliant behavior by any of the parties to the ISSG Ministers or those designated by the Ministers to determine appropriate action, including the exclusion of such parties from the arrangements of the cessation of hostilities, and the protection it affords them.

The United States and Russia are prepared, in their capacities as co-chairs of the Ceasefire Task Force and in coordination with other members of the ISSG Ceasefire Task Force as appropriate, to develop effective mechanisms to promote and monitor compliance with the ceasefire both by the governmental forces of the Syrian Arab Republic and other forces supporting them, and the armed opposition groups. To achieve this goal and to promote an effective and sustainable cessation of hostilities, the Russian Federation and the United States will establish a communication hotline and, if necessary and appropriate, a working group to exchange relevant information after the cessation of hostilities has gone into effect. In addressing incidents of non-compliance, every effort should be made to promote communications among all parties to restore compliance and rapidly de-escalate tensions, and non-forcible means should be exhausted whenever possible before resorting to use of force. The United States and Russia as co-chairs of ISSG Ceasefire Task Force will develop such further modalities and standard operating procedures as may be necessary to implement these functions.The United States and the Russian Federation together call upon all Syrian parties, regional states and others in the international community to support the immediate cessation of violence and bloodshed in Syria and to contribute to the swift, effective and successful promotion of the UN-facilitated political transition process in accordance with U.N. Security Council Resolution 2254, the February 11 Statement of the ISSG, the 2015 Vienna statements of the ISSG, and the 2012 Geneva Communiqué.