This relates back to the reason why NATO dropped Tripwire and moved to Flexible Response and deployed battlefield. & INF nukes in Europe to provide coupling & uncertainty.
Sergei Karaganov says that he is 99% sure that the U.S. will not retaliate if Russia launched a nuclear strike on a NATO country that supports Ukraine.
Karaganov's scenario appears to be in relation to Poland, as he says it would take a "madman" in the White House who "hates America" to sacrifice Boston for Poznan
Karaganov has made similar claims in the past about Article 5 of NATO having little practical value….