biological weapons are internationally banned, nevertheless some states occasionally utilize them to kill opponents such as traitors (poisoning is often a slow and painful death) or as an agent of terrorism.
it has been alleged the KGB in particular does not like traitors and will pursue them and kill them and poisoning is allegedly one of their preferred methods
Notable incidents
1978: Bulgarian journalist murdered with a poison-tipped umbrella on a London bridge
2004: Former president of Ukraine Viktor Yushchenko was poisoned with an “Agent Orange” chemical served in a rice dish that left him permanently disfigured.
2004: Anna Politkovskaya, Russian journalist drank a laced brew while flying to cover a crucial story. She was shot 2 years later on Putin's birthday.
2006: Alexandre Litvinenko was fatally poisoned in London by polonium poisoning
2018: UK government said that a Novichok agent had been used in an attack in the English city of Salisbury on 4 March 2018 in an attempt to kill former GRU officer Sergei Skripal and his daughter Yulia.
Charlie Rowley and Dawn Sturgess found a perfume bottle in the park and in June 2018 also developed severe symptoms and being found unconscious in their house with Dawn Sturgess later dying from the exposure.
2020: August 20, popular Russian opposition figure Alexei Navalny drank tea at a Siberian airport before boarding a flight to Moscow. An hour later, he had to be carried, screaming, from the aircraft bathroom and was rendered unconscious.