A second violation of Turkish airspace by a Russian warplane in two days has prompted Ankara to summon Moscow’s ambassador once again.
The US and Nato have condemned Russia’s actions, while Turkey has threatened to respond, raising concerns of a direct confrontation.
The Kremlin responded that the first incursion was merely a ‘mistake’, but added volunteer ground forces would join the fight.
The airspace over Syria is increasingly crowded, with Russian warplanes
as well as those of the US and its allies now flying combat missions over the same country for the first time since the Second World War.
With reports of civilian casualties following the Russian airstrikes, Turkey continues to press for no-fly zones in Syria, but Moscow remains opposed to such a step.
Russia, which supports embattled President Bashar al-Assad, claims to be targeting the so-called Islamic State group. However, the anti-Assad coalition says Moscow has targeted other militants, hitting few IS targets.