Without a sound, a smell or any warning, a new non-lethal weapon developed by the US military can repel crowds using an invisible electromagnetic beam that delivers a blast of intolerable heat up to a kilometer away. After years in development, the Active Denial System was recently demonstrated to media by the US army. The effect of the sudden heat is so repellant, the immediate instinct is to flee -- and quickly, as experienced by AFP at the presentation.Duration: 01:33
