• Eastern Ghouta damage seen from space
• 'My daughter's losing her hair from fear'

How many people have died?

Image copyrightGETTY IMAGES

The Syrian Observatory for Human Rights, a UK-based monitoring group with a network of sources on the ground, had documented the deaths of 353,900 people by March 2018, including 106,000 civilians.

The figure did not include 56,900 people who it said were missing and presumed dead. The group also estimated 100,000 deaths had not been documented.

Meanwhile, the Violations Documentation Center, which relies on activists inside Syria, has recorded what it considers violations of international humanitarian law and human rights law, including attacks on civilians.

It had documented 185,980 battle-related deaths, including 119,200 civilians, by February 2018.

What is the war about?

Image copyrightAFP

It is now more than a battle between those for or against Mr Assad.

Many groups and countries - each with their own agendas - are involved, making the situation far more complex and prolonging the fighting.