What are Novichok agents and what do they do?

What can the world do about Novichok?

Not much, perhaps. Russia, like most nations of the world, is a signatory to the Chemical Weapons Convention, which requires members to destroy any such weapons and the facilities that produced them. (Only Egypt, North Korea and South Sudan haven’t signed the accord; Israel signed but hasn’t ratified.) And Russia said last year that it had destroyed all its stocks of banned chemical weapons.