Russia's growing military involvement in the Syria conflict is expected to be high on the agenda of Nato defence ministers meeting in Brussels.

It comes after Nato member Turkey said Russian jets had violated its airspace.

Russia has fired missiles from a warship in addition to air strikes to support Syrian leader Bashar al-Assad.

But Moscow denies Westerns accusations that its strikes have mainly hit Assad opponents, some supported by the West, and not Islamic State (IS) militants.

BBC defence correspondent Jonathan Marcus says Nato aims to make clear it will respond to any challenge.

Analysis: Sarah Rainsford, BBC Moscow correspondent

Russia wants to show that Western policy in Syria has failed and there are other forces to be supported there, primarily President Bashar al-Assad.

The Kremlin's desire appears to be aimed at keeping America on the back foot.

The use of cruise missiles on Wednesday does not change the situation militarily - the same effect could have been achieved by air strikes.

But Mr Putin wants to project his power on the world stage, to show that he is a force to be reckoned with.

Ministers are expected to express their solidarity with Turkey. They will also address increased concern among Baltic member states following Russia's involvement in eastern Ukraine.

UK Defence Secretary Michael Fallon is expected to announce that Britain is ready to make a long-term troop deployment to the Baltic republics, our correspondent says.

But, he adds, ministers are meeting amid a deepening sense of crisis.

On Wednesday, Russia said it had launched missile strikes against IS from warships in the Caspian Sea - about 1,500km (930 miles) away.

Russia's foreign ministry also said Moscow was willing to establish contact with the Free Syrian Army - a Western-backed rebel group - to discuss fighting IS "and other terrorist groups".

But US Defence Secretary Ash Carter said coalition forces fighting IS in Syria would not co-operate with Russia.

"We believe Russia has the wrong strategy," he said. "They continue to hit targets that are not IS."

Airspace violations

Russia's air campaign in Syria has raised fears of accidental contact between Russian warplanes and those of the US-led coalition which have been targeting IS for the past year.

Pentagon officials revealed they recently had to carry out at least one "safe separation" manoeuvre to avoid a US jet coming too close to a Russian aircraft over Syria.

Nato Secretary-General Jens Stoltenberg said on Tuesday that Russia had not provided any real explanation for its violations of Turkish airspace, which "lasted for a long time" and "did not look like an accident".

He also pointed to reports of a build-up of ships and ground troops in Syria.

Russia's envoy to Ankara was summoned three times in response to recent incursions into Turkey's airspace.

Turkish President Recep Tayyip Erdogan warned the Kremlin that any "attack on Turkey means an attack on Nato".

"If Russia loses a friend like Turkey, with whom it has a lot of co-operation, it is going to lose a lot of things. It needs to know this," Mr Erdogan said.

The Syrian civil war began with an uprising against President Assad in 2011 that was brutally put down. It has since deteriorated into fighting between pro-government forces and various rebel groups - some of which also fight each other.

Amid the chaos, IS militants have seized swathes of territory in Syria and Iraq.