BEIRUT, Lebanon — A cease-fire in the Syrian civil war, negotiated by Russia and the United States, officially took effect at sundown Monday after a weekend of intensified fighting and a vow by Syria's president to retake the entire country.
Despite pessimism over how long the cease-fire would last, calm was widely reported after it took effect at 7 p.m. local time, but there were a few notable exceptions.
Less than an hour into the truce, residents in the divided northern city of Aleppo said via text message that a government helicopter had dropped explosive cylinders on a rebel-held district. And in the southern province of Daraa, a rebel faction said in a statement that it had killed four government soldiers. By midnight, opposition factions had reported 10 violations by government forces.
There have been extensive doubts expressed among many entangled in the conflict that the cease-fire, timed to coincide with the start of the Muslim holiday Eid al-Adha, will be respected.
Under the terms, if violence is significantly reduced for seven days, the United States and Russia will collaborate on new airstrikes against jihadi militants in Syria, and the Syrian air force will be barred from flying over insurgent-held areas.
The United States supports an alliance of rebel groups and Russia supports President Bashar Assad. But both countries share an antipathy for Islamic State and Nusra Front fighters who have seized parts of Syria and made it a magnet for jihadis.
Under the cease-fire deal, during an initial period, all attacks are to stop except Syrian government attacks on those two jihadi groups. The opposition has little trust in the Syrian government or Russia, which have often applied those labels to all of Assad's opponents. And government supporters doubt that the opposition groups will distance themselves from the extremists, as the Americans have promised.
There was also new confusion in the early hours of the cease-fire: Secretary of State John Kerry said the United States would be able to approve Syrian government strikes, but the State Department reversed those comments less than two hours later.
Assad used the hours before the cease-fire to promise victory in his country's 5-year-old civil war, punctuating his pledge by visiting a Damascus suburb that rebels surrendered last month.
Assad's visit to the suburb, Daraya, which had long been held by opposition fighters who want him deposed, was prominently reported by state TV other government news media.
The cease-fire is the second negotiated this year by Russia and the United States. The first, reached in February, collapsed within weeks.