President says terrorist from Gaza had USB with materials copied from al-Qaeda on 'dispersing cyanide'; meets with relatives of hostages, vows 'to do everything' to bring them home

Officials believe initiative will encourage other countries to comply with 1997 international Chemical Weapons Convention - which Israel has signed but not ratified

Damascus regime's representative in Organization for the Prohibition of Chemical Weapons says group's findings based on 'serious irregularities and defects'

Organization for the Prohibition of Chemical Weapons investigation finds 'reasonable grounds to believe' helicopter dropped two cylinders containing gas, killing 43

US president says such a step by Putin, who's losing ground in Ukraine, 'would change the face of war unlike anything since World War II'; 'They'd become even more of a pariah'

Head of rights group says lack of punishment for those behind Syrian attacks 'lowers the threshold for the use of such weapons' in the future

Armed forces minister James Heappey says 'all possible options' on the table if Putin uses chemical weapons, after Ukraine accuses Russia of using 'poisonous substance' in Mariupol

UK says its working to verify allegations Russia used chemical agent in Mariupol; UN also calls for greater protection of Ukrainian children, says two-thirds are displaced

US will not use chemical weapons even if Russia does, Sullivan says, as Kremlin accuses White House of 'diverting attention' and funding biological weapons labs in Ukraine

Ukrainian president tells G7 summit Russia already 'used phosphorus bombs against peaceful people'; NATO says it will increase chemical and nuclear defenses in Eastern Europe