Poland expelled several Russian diplomats on espionage charges earlier this year.

A number of Western nations expelled senior Syrian diplomats in protest.

Turkey and Japan later expelled Syrian diplomats, increasing the number of nations to do so to 13.

Expelling foreign diplomats in retaliation for espionage cases is a well-established international ritual.

Iran then proceeded to expel two British diplomats from the country, accusing them of "activities inconsistent with their diplomatic status".

The Iranian government stated that it would expel British diplomats for "unconventional behavior."

And governments would be required to expel many Libyan diplomats and restrict the movement of those allowed to remain.

The Israeli government retaliated by expelling Venezuelan diplomats from the country.

Their expulsion followed the Bush administration's decision to expel four Russian diplomats accused of espionage.

Earlier this month, Estonia and Russia each expelled two diplomats after trading accusations of espionage.