President Trump's national security adviser Michael Flynn resigned Feb. 13 after revelations that he had discussed sanctions on Russia with the Russian ambassador to the U.S. prior to Trump taking office. Here's what you need to know. President Trump's national security adviser Michael Flynn resigned Feb. 13. Here's what you need to know. (Deirdra O'Regan/The Washington Post)

President Trump’s national security adviser, retired lieutenant general Michael Flynn, resigned Monday night after “inadvertently brief[ing] the Vice President Elect and others with incomplete information regarding my phone calls with the Russian Ambassador [Sergei Kislyak].” Flynn resigned not because of his communications with the Russians, but rather because of his lack of discretion, misleading Vice President Pence about the nature of the exchanges, and, allegedly, opening himself up to blackmail by the Russians.

I wrote previously that back-channel contacts between Washington and Moscow are hardly unprecedented, either before presidential elections or during the transition period when power shifts from one party to another in the United States. The case of Richard Nixon in 1968-1969 furnished several clear examples of back-channel contacts, including exchanges between Nixon’s national security adviser, Henry Kissinger, and an identified KGB operative, Boris Sedov.

The differences show why the Nixon-Kissinger back channels were successful while Flynn resigned after less than three weeks.

First, Nixon and Kissinger synchronized the two back channels to the Soviets during the 1968 election and the transition period. This included the Kissinger-Sedov channel and also one between Nixon’s adviser and later ambassador to NATO, Robert Ellsworth, and the Soviet charge d’affaires, Yuri Cherniakov. Kissinger and Ellsworth acted with Nixon’s knowledge and the messages both men conveyed to the Soviets complemented and reinforced each other.