I have a brief column on Russia and the INF violation at the European Leadership Network - Don't help Russia destroy the INF Treaty. I don't think the main point I'm trying to make there is particularly controversial - while the United States appears to have reasons to call Russia's noncompliance, the infraction does not seem to be serious enough to press the case too forcefully. Indeed, leaning too hard would only help Russia slam the door and leave the treaty. For what it's worth, the U.S. administration made a smart move - now that the accusation has been made, Russia will find it more difficult to leave the treaty, even if it has been the idea all along. Not impossible, of course, but still.
A couple of points that are probably worth emphasizing. First, as I suspected, the alleged violation is not about the R-500 cruise missile or the Iskander system - U.S. officials were said to informally confirm that. Russian sources also say that the deployed Iskander/R-500 cruise missiles are treaty-compliant.
Second, the evidence presented by the United States to Russia is apparently rather thin - in fact, one Russian official said scornfully that they have to deal with Twitter messages and photos. Some sources say that the United States did not even tell Russia what particular cruise missile this is about. This is somewhat hard to believe, especially since Anatoly Antonov said (my apologies for a link to RT) that the issue was discussed at the end of 2013 and his understanding is that the United States accepted Russia's explanations. So, Russia must know what the issue is. As for the Twitter evidence, I wouldn't be surprised if the United States did not show all its cards - it is quite careful about protecting methods and sources.
In any event, it appears that Russia took the issue seriously and agreed to discuss it at what appears to be a fairly high-level meeting in September. We will see what that meeting produces. But as I understand, Russia is not in the mood to make any corrective actions - it wants the United States to take the accusations back and is perfectly prepared to leave the treaty if this doesn't happen.