A widespread calm appeared to be holding Tuesday in Syria as a cease-fire brokered by the U.S. and Russia continued into its second day.
“One thing we can say with confidence,” a senior U.S. official said during a background briefing late Tuesday afternoon, “is there has been a significant drop in the level of violence — not to zero, obviously, and we would like to see even a greater drop in the days to come.”
The commander of U.S. Air Forces Central Command, Lieutenant General Jeffrey Harrigian, told reporters at the Pentagon via teleconference Tuesday that the U.S. was now looking into the "possible establishment of a joint integration center with the Russians" to help with counter-Islamic State operations in Syria.
"The first step is the cessation of hostilities for seven days,” Harrigian said. “This is something the Russians and the [Syrian] regime must do, and they must do it properly."
Another senior U.S. official said “the only legitimate targets” for airstrikes are the Islamic State militant group and al-Nusra Front during this period.
“After the seven continuous days of reduced violence,” said this official, “when we set up the Joint Implementation Center, and then begin the first strike through the Joint Implementation Center, at that time the Syria regime air force would no longer be able to fly in any areas of Syria where there is opposition or al-Nusra Front present.”
Harrigan would not reveal details of where the potential center would be located, nor would he give specifics about what type of operational cooperation would occur, calling those details "premature."
He added that Russia's imprecise targeting methods and use of unguided, free-fall bombs were "clearly a concern of everybody involved," because the point of the cessation of violence and the potential coordination is to "protect civilians" in Syria.
The U.S. uses precision weapons, paired with surveillance, intelligence and intense training of its airmen, to strike IS targets. That way, Harrigian said, the U.S. can ensure it is putting "the right weapon on the right target at the right time" to avoid civilian casualties.
Syria’s ‘last chance’
The halt in fighting went into effect after sundown Monday. Hours later, U.S. Secretary of State John Kerry declared it "may be the last chance" to preserve the country fractured by five years of civil war.
The agreement was announced early Saturday in Geneva by Kerry and Russian Foreign Minister Sergei Lavrov. It is supported by a number of other nations, including Iran, which is a backer of the Syrian government, and Turkey, which wants the removal of President Bashar al-Assad from power in Damascus.
The cease-fire does not apply to the terror groups Islamic State or Jabhat Fateh al-Sham, previously known as Jabhat al-Nusra until it broke from al-Qaida and changed its name.
While some key insurgent leaders have criticized the agreement and expressed skepticism that it can succeed, they appear to be accepting the cease-fire in hopes that it can lead to political talks to remove the defiant president.
Some rebel groups in Syria are concerned about the targeting of Nusra, which they see as an ally in defending insurgent-held districts from a protracted Syrian government offensive in eastern Aleppo.
"The armed opposition in Syria now faces what is perhaps its biggest and most momentous decision since they chose to take up arms against the Assad regime in 2011," said Charles Lister, an analyst at the Middle East Institute and author of the book The Syrian Jihad.
Lister added that mainstream opposition forces "are extensively marbled or coupled" with Nusra forces on some of the front lines, from Deraa in the south to Damascus and throughout the northwest of the country.
The years of conflict have left hundreds of thousands of people dead in Syria and created about 12 million refugees, one of the world's worst humanitarian crises.
VOA's Jamie Dettmer contributed to this report.