(CNN) Malaysian police have revealed the substance that killed Kim Jong Nam was a highly toxic nerve agent more commonly used in warfare. VX nerve gas was first developed in the UK in the 1950s as a deadly chemical warfare agent, according to the Centers for Disease Control and Prevention (CDC). Experts say the formula has been replicated in the past by the US, Russia, Syria and Iraq. Here's what we know:What is it?

Source: CNN February 24, 2017 02:05 UTC