Since the end of the Cold War, a variety of leaked diplomatic cables, captured operatives and acts of espionage, like this summer’s hacking of the Democratic National Committee, have served as reminders that Russia and the United States continue to routinely spy on each other.

On Sunday, President Vladimir V. Putin, reacting to expanded sanctions against his country approved by Congress, ordered major cuts in the size of the American mission staff in Russia.

It was just the latest chapter in the history of diplomatic tit-for-tat.

December 2016: A Post-Election Accounting

On Thursday, the United States said it would expel 35 officials, the largest number of diplomats forced to leave since 2001, in retaliation for what American spy agencies said was Russian interference in the presidential election. A day later, Russian officials threatened to expel American diplomats in retaliation, but President Putin said American embassy staff would be permitted to stay.

June 2016: An Embassy Row

The United States expelled two Russian diplomats in retaliation for a bizarre episode outside the United States Embassy in Moscow, in which a Russian police officer attacked an American diplomat.