The largest al-Qaeda group in Syria, Jabhat al-Nusra, has called for terror attacks in Russia, while also urging strikes on Alawite villages and placing bounties on the heads of Bashar al-Assad and the Hezbollah leader, Hassan Nasrallah.
The threats from the group’s leader, Abu Mohammed al-Jolani, were made on Tuesday in a taped call to arms that condemned the Russian intervention in the conflict, which began a fortnight ago.
Jolani’s comments signal another escalation in the four-year war, in which his forces have become increasingly prominent.
“There is no choice but to escalate the battle and to target Alawite towns and villages in Latakia,” he said.
“And I call on all factions to hit their villages daily with hundreds of missiles, as they do to Sunni towns and villages.”
Jolani's comments came as rebel groups aligned to the Free Syria Army (FSA) said they were now receiving more anti-tank missiles than at any time in the last two years, with supplies from Saudi Arabia and the Gulf states ramping up since the Russian entry into the war.
The rockets had been instrumental in opposition gains in central Syria over the past 18 months, allowing rebels to push towards the coastal heartland of the Assad regime and partly negating the air superiority of government forces.
“The delivery is faster but they’re the same weapons they have given us before,” said Brigadier Ayad, a leader ofopposition unit Suqour al-Ghab.
“We are still asking our friends for the anti-aircraft rockets but they have never given us any.
“We have proven to Russia, the Syrian regime and even to our friends that the FSA is an active power on the ground.
“We have been showered with bombs but we managed to change the game and lure the regime into something that cost them dearly.
“Everybody is waiting to find the alternative to the regime before they take stronger action.”
US officials say that only two of an estimated 700 rockets supplied so far have ended up in the hands of al-Nusra or other jihadist groups, unlike a separate attempt to supply the fight against Islamic State.
That programme was abandoned last week after trained forces surrendered many of their weapons soon after crossing into Syria from Turkey.
The US and its coalition of air forces are continuing to target Islamic State in eastern Syria and north-west Iraq.
The coalition has accused Russia of attacking opposition groups instead of Islamic State, despite Moscow’s claims to the contrary.
The stepped-up supply of Saudi rockets, originally sold to Riyadh by the US, is being seen as a direct reaction to the Russian attacks, raising the spectre of a proxy war between the former Cold War foes.
Fighting on the ground near the Syrian president's heartland and further north in Idlib province has been more intense in the past week than at any point in the past two years.
Underscoring the stakes, Iran recently announced the death of one of its brigadier generals in the region, the most senior Iranian officer killed in combat in more than 30 years, while Hezbollah confirmed that two of its most senior members had also been killed.
All three men are believed to have died in fighting in Idlib, where Jabhat al-Nusra and the Islamist group Ahrar al-Sham are strongest.
In Syria’s northeast, the US on Monday dropped 50 tonnes of weapons and ammunition to the Kurdish YPG militia, for use in its campaign against Islamic State.
The YPG has been the most competent ground force to fight the jihadists, but was accused by Amnesty International on Tuesday of conducting a campaign of ethnic cleansing against Arabs and Turkmen in towns and villages it had conquered near the Turkish border.
Hezbollah officials in Beirut claim that Russia’s muscular role will secure central Syria, especially Latakia, Hama and Tartus, which are instrumental to the regime’s fortunes, and clear the way for a political solution.
However, rebel groups claim that Moscow’s moves will instead prolong the war, by driving some opposition rebels towards Islamist or jihadist groups and bog it down in a grinding, unwinnable campaign.
Russian officials said Washington has not replied to its requests for information about where rebel groups it backs are located.
US officials have justified their silence by claiming that the groups' locations have been targeted and that they do not want to be portrayed as allying with Moscow.
“We are not going to surrender and we will keep fighting till the last drop,” said Brigadier Ayad.
“Even the civilians who are living with us, being bombed day and night, prefer to die from the regime’s barrel [bombs] than living with their repression.”