Russia has begun a campaign of air strikes in Syria after the country's parliament authorised the use of military force in the war-torn nation on 30 September.

In this video, IBTimes UK explains why Russia has intervened in Syria's civil war now, whether its involvement is against Islamic extremists or all opponents of the country's beleaguered president, Bashar al-Assad, and what impact Russia's military involvement will have on Syria, Islamic State (Isis) and the refugee crisis in Europe.

Russia has moved troops, tanks, fighter jets and other equipment into Syria under the pretence of combating militant Islamic extremists in the region. But, as the Kremlin has now admitted, it has also launched air strikes hitting militant organisations opposed to Assad – not only IS – bolstering Western fears that Vladimir Putin's real purpose in Syria is to help Assad reclaim lost territory.

Russia supports Assad's regime in the ongoing four-year civil war as the country is one of its few remaining allies in the Middle East. While Western powers have weapon embargoes on Syria's government, Russia continues to supply Assad with arms.

Russia believes a strong Assad government is needed to repel the threat of IS in the region. But the US and others have spoken of a need for regime change, fearing any support for Assad could inspire rebels to join IS and lead to more refugees fleeing the country.