During the Vietnam war, the US illegally bombed Laos as part of a secret war to disrupt Vietcong supply routes. 30 years later, 78 million unexploded cluster bombs remain scattered across the country, placing thousands at risk of death or injury every day. 111 countries gathered in Dublin this week to adopt a treaty banning cluster bombs. 5 countries - the US, Russia, Israel, India and Pakistan - were notable in their absence.