Pyotr Verzilov, the Pussy Riot member hospitalized late Tuesday night in a suspected case of poisoning, is Canadian.

Russia wants Britain to provide information about the pets that lived in the house of the Russian former spy who was poisoned with nerve agent in England.

The daughter of a Russian ex-spy poisoned in a nerve-agent attack is out of critical condition — an unexpected piece of good news in a chilling mystery that has sparked an international crisis.

Experts say the recent mass exodus of diplomats is largely intended make clear to Putin's administration that actions such as these will not be tolerated by the West.  

Russia says it has expelled two American diplomats who it claims were working undercover for the CIA, in retaliation for the U.S. expulsion of two Russians.