Russia's growing military involvement in the Syria conflict is expected to be high on the agenda of Nato defense ministers meeting in Brussels, BBC News reports.

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