A ceasefire deal between Syrian government forces and rebels that took effect at midnight held early on Friday, after initial isolated clashes and gunfire, a monitoring group and a rebel official said.
The truce was violated almost immediately after it came into effect as the warring sides clashed in the northwest of the country.
However, the Syrian Observatory for Human Rights said hours later that the general “calm continues”.
A rebel official in the Jaish al-Nasr group said there had been “some shelling during the night, but today it’s stopped ... until now the situation is good.”
Earlier on Thursday, Russian president Vladimir Putin had announced an immediate ceasefire plan for Syria that will pave the way for peace talks between the government of Bashar al-Assad and rebel opposition groups, raising hopes of a breakthrough in the bitter war.
Russia and Turkey are to guarantee the truce, Mr Putin said during a meeting with the Russian defence and foreign ministers in Moscow.
If it holds, the ceasefire could mark a turning point in a war that has claimed hundreds of thousands of lives and triggered the biggest refugee crisis since the second World War.
Speaking at a televised meeting with the Russian defence and foreign ministers in Moscow on Thursday, Mr Putin said the Syrian government and opposition groups had signed three documents covering the ceasefire itself, measures to monitor the truce and a declaration of readiness to begin peace talks.
The Russian president underscored the complexity of bringing an end to the Syrian conflict, warning of the delicate nature of the latest truce.
“We understand perfectly well that all the agreements reached are very fragile, they will demand special attention and patience, a professional approach and constant contact with our partners,” he said.
Mr Putin said the Syrian government and rebel groups would participate in planned peace talks in Astana, the capital of Kazakhstan, but did not give a date for the start of negotiations that will be separate from intermittent United Nations-backed peace talks.
There was also confusion over which rebel groups had signed up.
Russia launched an aerial bombing campaign in Syria in late September 2015 after Mr Assad, its long-time ally, appealed for help.
With support from the Russian air force, Syrian troops have made headway on the ground, recapturing territory from opposition rebels seeking to oust Mr Assad.
Syria’s defence ministry announced a nationwide halt to fighting on Thursda following “victories and advances” by the Syrian army.
In a statement posted on the state-controlled Syrian Arab News Agency, the ministry said “terrorist organisations”, including Islamic State and the country’s al-Qaeda affiliate, Jabhat Fateh al-Sham, were not included in the ceasefire deal.
Regional powers
The ceasefire plan comes after a week of intense talks between regional powers Russia, Turkey and Iran.
The US has been sidelined from the process, reflecting Russian and Turkish frustration over Washington’s policy in Syria.
Russian officials have said the US would not be invited to the talks, although that might change after Donald Trump, US president-elect, takes office next month.
The complexity of the two countries’ relationship was underlined by news on Thursday night that the Obama administration is to expel 35 Russian diplomats over cyberattacks during the US election race.
Disagreements remain between the three countries backing the latest attempt to end the hostilities in Syria and could yet undermine the peace process.
Turkey has insisted on the ousting of Mr Assad as a precondition of a settlement.
Iran is opposed to Turkish demands that Lebanese Hizbullah fighters, who have been backing Mr Assad, withdraw from Syria.
Mr Putin agreed on Thursday to a Russian defence ministry proposal to reduce Russia’s military presence in Syria.
However, he pledged that the Kremlin would continue to support the Syrian government and to fight international terrorism.
Additional reporting: Reuters