The Syrian military has started using new types of air and ground weapons supplied by Russia, a Syrian military source said yesterday, underlining growing Russian support to Damascus that is alarming the United States.

“The weapons are highly effective and very accurate, and hit targets precisely,” the source said in response to a question about Russian support. “We can say they are all types of weapons – be it air or ground.”

The source said the army had been trained in the use of the weapons and was now deploying them, declining to give further details other than saying they were “new types”.

The Russian government said yesterday its military support for Damascus was aimed at fighting terrorism, safeguarding Syria’s statehood and preventing a “total catastrophe” in the region.

Assad launches heavy air strikes on Islamic State city of Raqqa

It includes a larger Russian military presence on the ground in Syria, where President Bashar al-Assad has faced increased pressure this year from rebels fighting to topple him, but its full scope and intentions remain unclear.

Washington, which wants al-Assad gone from power, has said it believes Russia is undertaking a significant military buildup which could exacerbate the war.

The US, along with Saudi Arabia and Turkey, have supported insurgents battling to unseat al-Assad, whose foreign military backing has so far come mostly from Iran and its Lebanese ally Hizbollah.

A US-led coalition is also bombing Islamic State militants in Syria and Iraq, raising the prospect of a potential clash between US and Russian air forces.

In a possible sign of newly assertive posture by al-Assad, the Syrian air force launched heavy air strikes on Aleppo and the Islamic State-held city of Raqqa, an important base of operations for Islamic State in Syria often targeted by the US-led coalition.

The UK based Syrian Observatory for Human Rights said at least 18 were killed in the raids that hit several areas in the city and it’s outskirts, including a maternity hospital.

An Airbus Defence and Space satellite image courtesy of Stratfor, a geopolitical intelligence and advisory firm in Texas, shows a Russian AN-124 Condor transport plane at the airbase in Latakia, Syria. The US has identified a number of Russian helicopters at a Syrian airfield. Russia has been sending about two military cargo flights a day to Latakia on the government-controlled Syrian coast, US officials say.

The government, which by al-Assad’s own admission faces a military manpower problem, is seeking to shore up control over the cities of the west after losing much of the rest of Syria to an array of insurgents including Islamic State.

The Obama administration said on Wednesday it was considering how to respond to a Russian proposal for military talks over Syria, which may be about “deconfliction” – ensuring that US and Russian aircraft do not come into conflict in Syria.

Russia says al-Assad should be part of international efforts to fight Islamic State. The US believes he is part of the problem and rejects that idea.

The war has killed 250,000 people. Four million people have fled Syria and almost twice as many are displaced inside it. Tens of thousands of Syrian refugees have been arriving in Europe.

Activists said Syrian government war planes had mounted at least 12 air strikes in Raqqa, often described as Islamic State’s de facto capital.

The strikes hit close to at least four Islamic State offices, including one used by its self-appointed religious police force, said an activist in Raqqa who was contacted via the internet and declined to be named for security reasons.

Islamic State imposed a curfew in two parts of the city.