The "moderate" Syrian rebels Washington is set to throw its weight behind are a ragtag collection of outgunned factions weakened by a war on several fronts -- against the regime and jihadists.

- Who are the rebels?

Turkey on Friday reopened its border with Syria to Kurds fleeing Islamic State (IS) militants, saying a "worst-case scenario" could drive as many as 100,000 more refugees into the country.

Groups of visibly exhausted Syrian Kurds, most of them women and children who had fled their homes on foot, were shown on live television crossing into the southeastern Turkish village of Dikmetas, under tight security.

Syria's opposition said Thursday that 16 children who died during a measles vaccination campaign in the mostly rebel-held province of Idlib had been given an anaesthesia additive by mistake.

"Reports point to the possibility of human error which led to atracurium being used in place of the solvent which should have been used with the vaccine," said opposition government chief Ahmad Tohme.

As Islamic State fighters have advanced in neighboring Syria and after the brutal beheading of two of its soldiers, Lebanon has reacted with fear but also dark humor mocking the jihadists.

After a deadly battle between Lebanese troops and jihadists flowing from Syria into the town of Arsal in August, many Lebanese started greeting each other with a characteristic mixture of concern and jest. 

Warnings that the Islamic State organisation may be plotting to attack Pope Francis during his visit to mostly-Muslim Albania on Sunday have been shrugged off by the Vatican.

Qatar's envoy, who is tasked with mediating the release of Lebanese soldiers and policemen taken captive by jihadists from a border town, is expected to arrive in Beirut on Friday amid hopes by their families that the hostages will escape beheading.

The envoy, a Syrian, is scheduled to meet with members from the Muslim Scholars Committee and officials close to al-Qaida-linked al-Nusra Front away from media spotlight.

A dramatic change of tone in the latest hostage video released by the Islamic State has convinced experts that the jihadist group is isolated and fearful of a U.S. assault.

President Barack Obama on Thursday hailed Congress for backing his plan to arm moderate Syrian rebels and France for signing off on air strikes in Iraq, victories for his campaign to destroy the Islamic State group.

U.S. warplanes meanwhile hit an Islamic State group training camp in Iraq in their first strike not directly supporting Iraqi or Kurdish forces as Washington cranked up  pressure on the Sunni extremist group.

After nearly two decades on the frontlines against Muslim insurgents in the Philippines' violence-plagued south, Army Captain Teodoro Nicor is looking forward to guarding a war zone abroad.

Federal police are to take over security at Australia's parliament, Prime Minister Tony Abbott said Friday, describing the building as a potential terror target, following revelations that Islamic State jihadists were plotting "demonstration executions".

"Parliament House certainly is a potential target," Abbott said.