Explanation from @georgewherbert seems to fit all the contradictory statements:
US "not an ICBM" technically true based on range, but RS-26 is nominally an ICBM. Putin's "new type of weapon" probably an exaggeration, but a previously unacknowledged role or variant
Notably there were rumors RS-26 would be used in the days before, and the US embassy closure for an unspecified "specific information of a potential significant air attack" was likely related