Syria's weapons: How did we get here?

Syria has destroyed all its declared chemical weapons mixing, filling and production facilities, and all of the chemical weapons at inspected sites have been placed under seal, the Organisation for the Prohibition of Chemical Weapons said Thursday.

The watchdog body's announcement of the facilities' destruction means that the first deadline has been met in an ambitious program to eliminate the country's entire chemical weapons stockpile by the middle of next year.

The joint United Nations-OPCW mission visited 21 out of 23 sites, the OPCW statement said, and 39 of the 41 facilities at those sites.

The remaining two sites were too dangerous for the inspectors to go to, it said, but Syria had declared those sites as abandoned. The chemical weapons equipment there was moved to other sites, which were inspected.

Read: Syria has met first chemical weapons destruction deadline, OPCW says

Becky reports on the key events in the timeline of Syria's chemical weapons.