
Syrian media reports that Israeli warplanes have carried out dozens of attacks across the country, including the capital Damascus.
The UK-based Syrian Observatory for Human Rights (SOHR) said there were more than 100 attacks on military targets. A research center with suspected links to chemical weapons production was among the sites hit, according to local media reports.
Israel says it is acting to stop weapons falling "into the hands of extremists" after the overthrow of the Assad regime.
On Monday, the UN Security Council met to discuss the situation in the country following the fall of President Bashar al-Assad and said they would work on a statement in the coming days.
"The council, I think, was more or less united on the need to preserve the territorial integrity and unity of Syria, to ensure the protection of civilians, to ensure that humanitarian aid gets to the population in need," Russian Ambassador to the UN Vassily Nebenzia told reporters.
The SOHR says there have been hundreds of Israeli airstrikes in the past two days, including on a site in Damascus said to be used for missile development by Iranian scientists. The strikes come after the UN chemical watchdog warned authorities in Syria to ensure suspected chemical weapons stockpiles are secure.
The use of chemical weapons is prohibited under international humanitarian law. It is not known where or how many chemical weapons Syria has, but it is believed that former President Bashar al-Assad maintained a stockpile.
Syria signed the OPCW Chemical Weapons Certificate in 2013, a month after a chemical weapons attack on the outskirts of the capital, Damascus, that left more than 1,400 people dead. Horrifying images of victims writhing in agony shocked the world. Western powers said the attack could only have been carried out by the government, but Assad blamed the opposition.
Despite the OPCW and the UN destroying all 1,300 tons of chemicals that the Syrian government claimed, chemical weapons attacks in the country continued. A 2018 BBC analysis confirmed that between 2014 and 2018, chemical weapons were used in the Syrian civil war at least 106 times.