Syria's opposition has demanded U.N. inspectors immediately investigate a besieged rebel-held region hit by an alleged chemical weapons attack that killed hundreds of people.
Following is a timeline of some of the major chemical attacks over the past century:
* WORLD WAR ONE
- In April 1915, Germany mounted the first large-scale chemical attack in warfare when it opened canisters of chlorine upwind of French, Canadian and Algerian troops at Ypres in Belgium, allowing prevailing winds to spread the gas.
- By the end of the war in 1918, the estimated death toll from the use of chemical weapons - mainly chlorine, phosgene and mustard gas, used by both sides - was around 90,000, with more than one million casualties overall.
* ITALO-ABYSSINIAN WAR, 1935-36
- Ignoring the 1925 Geneva Protocol which it signed along with 15 other major countries committing them not to use chemical agents in war, fascist Italy unleashed mustard gas during its invasion of Ethiopia in the second Italo-Abyssinian War. According to the Stockholm International Peace Research Institute (SIPRI), a precise casualty toll may never be determined. But it said a Soviet estimate stated that 15,000 of the 50,000 Ethiopian casualties in the war were from poison gas.
* IRAN-IRAQ WAR, 1980-88
- Iraqi leader Saddam Hussein used mustard and nerve gas against "human waves" of Iranian ground forces and poorly trained volunteers, causing over one million casualties during the war, according to the Non-Proliferation Review.
- In March 1988, after some Kurdish guerrillas joined an Iranian offensive, Iraqi warplanes bombed the Kurdish town of Halabja in Iraq near the Iranian border with mustard and nerve agents, killing up to 5,000 people, mostly civilians.
* SARIN ATTACKS IN JAPAN, 1994-95
- The Aum Shinrikyo doomsday cult in Japan perpetrated two attacks with the nerve gas sarin, one in Matsumoto in central Japan and another on the Tokyo subway, killing a total of 20 people and injuring thousands. The incidents refocused world attention on the potential use of chemical arms by terrorists.
* TREATY ON CHEMICAL WEAPONS, 1997
- The Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction (otherwise known as the Chemical Weapons Convention or CWC) is ratified in 1997.
- The Convention is unique - the first multilateral treaty to ban an entire category of weapons of mass destruction (WMD) and it also provided for the international verification of the destruction of these arms.
Sources: Reuters/Organisation for the Prohibition of Chemical Weapons/SIPRI here here
(Reporting by David Cutler, London Editorial Reference Unit, writing by Mark Heinrich; Editing by Jon Boyle)