Kim Hjelmgaard

USA TODAY

Syrian state media said Tuesday that President Bashar Assad accepted a temporary "cessation of hostilities" deal brokered by the United States and Russia on Monday.

The embattled president said he would accept a deal that would cover his military forces and armed opposition groups, but exclude the Islamic State and al-Qaeda-linked Nusra Front terrorist organizations, State-affiliated news agency Sana said.

The pause in fighting takes effect Saturday. A previous deal to halt fighting collapsed.

United Nations-sponsored peace talks between the Syrian government and a delegation representing opposition groups — the High Negotiations Committee — broke down on Feb. 3. Those talks may resume on Feb. 25.

The HNC said Monday it too would accept the U.S.-Russia cease-fire plan provided Assad halted his military campaign against 18 rebel-held areas. Assad reserved the right to retaliate against rebel groups for any violation of the cease-fire.

Washington has conceded that the agreement will not be easy to execute.

"We are all aware of the significant challenges ahead," U.S. Secretary of State John Kerry said in a statement on Monday.

President Obama and Russian President Vladimir Putin discussed the plan on the phone. Obama urged Putin to put pressure on the Syrian government to "alleviate the suffering of the Syrian people." Afterward, Putin appeared on television and called the agreement "a real step forward that can stop the bloodshed."

Speaking to USA TODAY on Tuesday, Michael Klosson, vice president for policy and humanitarian response at Save the Children, said that while it was good that something was being done, “we should withhold our applause.”

“The true measure is the reduction of suffering of Syrians on the ground. Is aid getting through to those who need it? The tunnel is still very dark,” he said.

An estimate from the Syrian Center for Policy Research found that the five-year-old civil war has led to the deaths of 470,000 people. The figure is twice the amount used by the United Nations, which has stopped counting amid unreliable data.

More than 4 million Syrian refugees have fled the country amid the fighting, many of them to Turkey. Numan Kurtulmus, Turkey’s deputy prime minister, told journalists on Tuesday that Ankara backs the new cease-fire plan but that Turkey would continue shelling Syrian Kurdish positions in Syria if it was attacked.

Syrian Kurdish fighters have proved useful to the U.S.-led coalition fighting the Islamic State but Turkey considers some of them to be terrorists because of their links to Kurdish rebels who are seeking greater autonomy from the Turkish government.

U.S., Russia agree to new Syria cease-fire starting Saturday