Now we know what the message was, and also why the visit lasted only a few hours.
According to the WSJ, citing people briefed on the matter, CIA Director John Ratcliffe visited Moscow to warn Putin not to attack NATO countries.
Obviously, there's no official confirmation yet, as neither the Russian nor the U.S. government will ever provide further details regarding this visit.
What is certain is that Western intelligence information is correct, there's a real risk that Russia will attempt to conduct provocations or mini-attacks against NATO countries to test the alliance.
We don't know when this will happen, though.
The message was delivered by CIA Director John Ratcliffe.
A short while ago, the USAF C-17A Globemaster III that landed at Moscow's Vnukovo Airport departed the Russian capital after about 10 hours.