In April, Syrian President Bashar al-Assad's air force dropped bombs containing sarin nerve gas on a rebel area in northern Syria. Around 100 people were killed and hundreds more injured, including a number of children.
The slaughter highlighted the renewed threat of chemical and biological weapons. Both Assad's forces and rebel groups have used chemical weapons in Syria, demonstrating the dangers of proliferation. Meanwhile new gene editing technologies allow for the creation of more virulent and deadly bio-weapons.
On this edition of Global Journalist, a look at the history and future of chemical and biological weapons.