Russian warships in the Mediterranean Sea have fired cruise missiles at targets near Aleppo, a further sign of Moscow's broadening military effort in Syria days after it began to fly bombing missions from an airbase in Iran.
Russian air power had helped Syrian President Bashar al-Assad make steady advances against rebels seeking to oust him since Moscow's intervention a year ago, but a recent insurgent advance in Aleppo has checked that momentum.
In northeastern Syria, warplanes from a US-led coalition flew patrols on Thursday to protect local ground forces they back against Syrian government airstrikes that are targeting the Kurdish city of Hasaka, the Pentagon said.
Russia's three cruise missile launches were its first against targets in Syria from the Mediterranean, with previous ones made from its Caspian Sea fleet. On Tuesday Russian bombers began flying missions in Syria from Hamedan air base in Iran.
Russia's Defence Ministry said the strikes targeted the Islamist militant group Jabhat Fatah al-Sham, known as the Nusra Front until it broke formal ties with al-Qaeda last month before playing a big role in the sudden rebel advances in Aleppo.
The upsurge in fighting and airstrikes in and around the city, split between government-held west and rebel-held eastern sectors, has prompted growing international concern, galvanised by pictures on Thursday of a dazed, bloodied child.
The plight of civilians in Aleppo has been aggravated in besieged areas by dire shortages of basic goods, leading the World Food Program to warn of a "nightmarish" situation.
On Thursday Russia said it supported a proposal for a weekly 48-hour pause in fighting in Aleppo to allow aid to reach the besieged areas.
On Friday, the main umbrella group for the Syrian opposition also cautiously welcomed the idea provided the UN monitored the truce and enforced compliance.
Syrian Kurdish authorities then evacuated thousands of civilians from Kurdish areas of Hasaka following government air strikes, a spokesman for the Kurdish YPG militia, an integral part of the US-backed Syrian Democratic Forces (SDF), said.
Hasaka is divided into zones of Kurdish and Syrian government control and fighting between them has killed dozens of civilians in the past 48 hours, YPG spokesman Redur Xelil said.
In Aleppo, continuing clashes between rebels and the Syrian army and allied militias were fiercest in the southwest of city, the Syrian Observatory for Human Rights, a UK-based monitor of the five-year-old civil war, said on Friday.
It added that air strikes and shelling in and around Aleppo had killed 422 civilians, including 142 children, this month.