The Syrian opposition accuses President Bashar Assad’s military of violating the truce the United States and Russia brokered in February by bombing those areas. Kerry said the United States and Russia had shared their announcement with the other countries participating in stalled talks to end Syria’s long-running civil war.

Secretary of State John Kerry, in Paris for meetings on the Syria crisis, said Russia had also committed to limiting the Syrian government’s ability to fly over civilian areas.

PARIS — The United States said Monday that a new agreement with Russia would replace localized, piecemeal cease-fires in Syria with a revived, nationwide truce, as world leaders struggled to get faltering peace talks back on track.


But Kerry cautioned that the agreement would mean little if it’s not backed up by the parties on the ground.

‘‘These are words on a piece of paper. They are not actions,’’ Kerry said. ‘‘It is going to be up to the commanders in the field and the interested parties — which includes us.’’

It was unclear whether the announcement would effectively stem the violence, or whether Russia and Syria even saw it the same way.

In Damascus on Monday, a limited cease-fire in the northern Syrian city of Aleppo and its surrounding countryside was extended for the third time, for another 48 hours starting at 1 a.m. Tuesday. The extension came a couple of hours before an earlier cease-fire was set to expire. It was not clear if other announcements regarding cease-fires in the rest of the country would follow.

A joint US-Russia statement made no explicit reference to ending the practice of pursuing partial truces.

The extremist groups Nusra Front, Al Qaeda’s branch in Syria, and its more powerful rival, the Islamic State, are not included in the cease-fire agreement.

An intricate landscape where government troops, extremist groups, and Western-backed rebels operate, often side by side, has made the cease-fire reached in late February difficult to sustain and monitor.


Elusive political talks have also hardened positions, endangering the cease-fire. World leaders are struggling to get faltering peace talks back on track.

Aleppo has seen the worst violence since the February cease-fire collapsed. Nearly 300 civilians were killed in several days.

Syria’s military said the new cease-fire would expire at midnight Wednesday.

There were limited breaches of the most recent five-day cease-fire from both sides.

Multiple air raids on Monday struck rebel-held areas, while shelling hit government-controlled parts of Aleppo, two opposition monitoring groups and Syrian state media reported.

The Britain-based Syrian Observatory for Human Rights and the Local Coordination Committee said the airstrikes hit several areas in Aleppo, including the neighborhood of Rashideen. Monday’s airstrikes came a day after opposition fighters shelled the government-held neighborhood of Midan, killing a child, state media and activists said.

Opposition activists also reported air raids and shelling in Khan Touman, just south of Aleppo, which was captured Friday by a coalition of insurgent groups including Nusra Front. The battle left at least 13 members of Iran’s elite Revolutionary Guards dead, as well as troops and pro-government gunmen.

The town was captured by a coalition known as Jaish al-Fatah, or Army of Conquest, an ultraconservative group led by Nusra Front, and the jihadi militias Jund al-Aqsa and Ahrar al-Sham.