IBTimes UK speaks with intelligence consultant David Otto − CEO of UK-based global security provider TGS Intelligence Consultants − on how the crisis in Syria has worsened following the military intervention of Russia, which said it aimed to tackle members of the Islamic State (Isis) and other Islamist terror groups.

According to Otto, a coalition backing the rebels on one side and another one supporting Syrian President Bashar al-Assad on the other, make it difficult to distinguish between terrorists and so-called "freedom fighters". It suggests that a solution to the conflict is far from being achieved. Otto added that the current scenario will allow IS to take advantage of the crisis and gain more power.

In 2011, Assad faced an armed uprising that erupted in the wave of pro-democracy protests across the Middle East, known as the "Arab Spring". Assad tried to crush the uprising with the support of its allies.

The country quickly descended into war − still continuing today − resulting in the death of more than 240,000 people, with civilians often being targeted by air and ground attacks from both sides. As a result, more than 4 million people have fled the country seeking asylum.

Who supports whom in the Syria war?

Pro-Assad coalition:

Allies of the Syrian government that support its fight against rebels to keep Assad in power are: Iran, Russia and Hezbollah, a Lebanese militant group considered a terrorist organisation by both the US and the EU.

Coalition that backs anti-Assad rebels

A coalition that backs some of the anti-Assad groups comprises US, Saudi Arabia, Qatar and Turkey. Rebel groups in Syria include:

The Free Syrian Army (FSA): Formed by defected soldiers and officers in 2011. Originally considered a moderate, pro-democracy group, it later became more extremist as the war intensified. In 2012, Human Rights Watch accused the FSA of carrying out war crimes including torture and extrajudicial executions.

Islamic State (Isis): It aims to expand its Islamic caliphate − declared in Mosul, Iraq, in 2014 − throughout the controlled areas in Syria and Iraq. It has fought intermittent battles with other Sunni militias including Jabhat al-Nusra since splitting with al-Qaeda. It is the target of military campaigns carried out by both the US-led coalition and Russia, although the latter has been accused of carrying out 90% of its air strikes against non-Isis targets.

Ansar Sharia: An umbrella organisation made up of numerous Islamist groups, such as al-Qaeda's official Syrian offshoot Jabhat al-Nusra.

People's Protection Units (YPG): Formed of Syrian Kurds, it has strong links with Turkey and Iraqi Kurdistan's Kurdistan Workers' Party (PKK). It fought against IS in 2014 as the group expanded to northern Syria.

The Southern Front: Syrian rebel coalition consisting of some 58 Syrian opposition factions.