So we have one attempted murder, and possibly one successful murder, of Russian spies who defected to Britain. The attempted murder used a nerve agent, the other man may have been killed using the same chemical.

Can you name the last time a nerve agent was used to kill someone? Who was killed, and the country that was alleged to be the source?

Hint: It's a country whose leader may soon be in high-level talks with the US, and whose position might be improved if relations between other countries and the USSR were degraded.