Syria war of 2018

Why is there a war in Syria?

What began as a peaceful uprising against Syria's President Bashar al-Assad seven years ago became a full-scale civil war that has left more than 340,000 people dead, devastated the country and drawn in global powers.

How did the war begin?

Long before it started, many Syrians complained about high unemployment, widespread corruption, a lack of political freedom and state repression under President Bashar al-Assad, who succeeded his father, Hafez, in 2000.

In March 2011, pro-democracy demonstrations inspired by the Arab Spring erupted in the southern city of Deraa. The government's use of deadly force to crush the dissent soon triggered nationwide protests demanding the president's resignation.

As the unrest spread, the crackdown intensified. Opposition supporters took up arms, first to defend themselves and later to expel security forces from their areas. Mr Assad vowed to crush "foreign-backed terrorism" and restore state control.

The violence rapidly escalated and the country descended into civil war as hundreds of rebel brigades were formed to battle government forces.

Why has the war lasted so long?

In essence, it has become more than just a battle between those for or against Mr Assad.

A key factor has been the intervention of regional and world powers, including Iran, Russia, Saudi Arabia and the United States. Their military, financial and political support for the government and opposition has contributed to the intensification and continuation of the fighting, and turned Syria into a proxy battleground.

External powers have also been accused of fostering sectarianism in what was a broadly secular state, pitching the country's Sunni majority against the president's Shia Alawite sect. Such divisions have encouraged both sides to commit atrocities that have not only caused loss of life but also torn apart communities, hardened positions and dimmed hopes for a political settlement.

Jihadist groups have also seized on the divisions, and their rise has added a further dimension to the war. Hayat Tahrir al-Sham, an alliance formed by what was once the al-Qaeda-affiliated al-Nusra Front, controls large parts of the north-west.

Meanwhile, the Islamic State (IS) group seized control of large swathes of north-eastern Syria. It now controls only a few isolated pockets of territory after being driven from its urban strongholds by Russian-backed government forces, Turkish-backed rebel brigades, and a Kurdish militia alliance supported by the US.

Thousands of Shia militiamen from Iran, Lebanon, Iraq, Afghanistan and Yemen are fighting alongside the Syrian army, in order, they say, to protect Shia holy sites.

Why are so many outside powers involved?

Russia, for whom President Assad's survival is critical to maintaining its interests in Syria, launched an air campaign in September 2015 with the aim of "stabilising" the government. Moscow stressed that it would target only "terrorists", but activists said its strikes repeatedly hit Western-backed rebel groups and civilian areas.

The intervention has turned the tide of the war in Mr Assad's favour. Intense Russian air and missile strikes were decisive in the battle for rebel-held eastern Aleppo in late 2016, while Russian special forces and mercenaries helped break the long-running IS siege of Deir al-Zour in September 2017.

Two months later, President Vladimir Putin ordered a partial withdrawal of Russian forces, but they have continued to conduct air strikes across the country.

Shia power Iran is believed to be spending billions of dollars a year to bolster the Alawite-dominated government, providing military advisers and subsidised weapons, as well as lines of credit and oil transfers. It is also widely reported to have deployed hundreds of combat troops in Syria.

Mr Assad is Iran's closest Arab ally and Syria is the main transit point for Iranian weapons shipments to the Lebanese Shia Islamist movement Hezbollah, which has sent thousands of fighters to support government forces.