The State Department announced in a Thursday fact sheet that the US will initiate "Four lawful countermeasures in response to the Russian Federation's ongoing violations of the New START Treaty" which it deemed "proportionate" and "reversible." Further, Russia has been notified in advance of the move.
But the fact sheet underscored that "The United States continues to abide by the treaty's central limits, and to fulfill all of its New START obligations that have not been included within these countermeasures."
Crucially, the most important of the countermeasures bans all Russian inspectors from visiting US territories. This was the most important aspect to the agreement, given that among the nuclear reduction treaty's chief aims is to ensure inspection and monitoring of each side's nuclear arsenal by the other. However, it had already been on pause since 2020 in relation to Covid restrictions and lockdowns.