The INF treaty violation dispute just took a few very interesting turns. It started with Sergey Ryabkov's briefing in Moscow on Monday. At some point there was a rumor that the United States is going to formally announce its withdrawal from the treaty on Tuesday. That proved to be a false alarm, and instead we saw results of U.S. administration's effort to present a better case to its NATO allies. That effort brought a statement from the Dutch government, that said that it independently confirmed that Russia is violating the INF Treaty. Then the German intelligence services assessed U.S. evidence as "convincing." And the week closed with a statement released by the Director of National Intelligence, Daniel Coats.

The DNI statement finally provided the official U.S. theory of the violation:

Russia initially flight tested the 9M729 - a ground based missile - to distances well over 500 kilometers (km) from a fixed launcher. Russia then tested the same missile at ranges below 500km from a mobile launcher. By putting the two types of tests together, Russia was able to develop a missile that flies to the intermediate ranges prohibited by the INF Treaty and launches from a ground-mobile platform.

This is not exactly news - this was the theory that first appeared back in 2014 and then was very much confirmed by the people who knew details of the case. Not in so many words, of course, but there was enough information out there to put it all together:

I was told that the information that the Unites States gave to Russia at the early stages of the dispute included a description of two tests--first, the missile was tested from a treaty-compliant launcher (fixed land-based used for SLCM tests) and then, a a few days later, it was tested again, from a noncompliant one (land-based mobile).

I think I have to ask - What was so secret about it? There is absolutely nothing in the DNI statement that could not be released back in 2014. And it would have probably helped find a way to deal with the problem. Instead, attempts to find out what happened were met with dismissive "If only you knew what we know" or "You were not in the room when we discussed the intelligence" kind of response. All this helped bring us to the point when we are discussing the impending collapse of the INF Treaty.

Russia, of course, insists that it did nothing wrong and the missile tested from a fixed launcher is different from that tested from a mobile launcher. Ryabkov, in fact, addressed this more or less directly is his presentation:

[The United States] assumed that Russia could carry out tests of a missile with a smaller amount of fuel than provided for by the design. For our part, we highlighted the specifics of the fuel system of our missile, which preclude such experiments.

What he seems to be referring to is the possibility that the tests from a mobile launcher were made appear treaty-compliant by simply not filling up the fuel tank to the full (the "cколько топлива нальем, тому договору и будет соответствовать" scenario). Whatever is the case, the United States described Russia's measures to ensure that the mobile-launcher tests stay below the INF treaty limit as "attempts to obfuscate the nature of the program." But Russia probably considers them legitimate measures that ensure that the program is in compliance with the letter of the treaty.

Given the confidence with which the United States insists that Russia is in violation, they probably have some fairly solid intelligence. This could be human intelligence, intercepts of phone calls or maybe of the telemetry - something that is fairly good but cannot be shown publicly. Or maybe not - judging by how long it took to convince the Europeans that the violation is real, the evidence may not be all that solid. At this point I wouldn't give U.S. administration the benefit of the doubt. But I don't see a reason to trust the Russian government either.

Where does this leave us and is it possible to find a way to keep the INF Treaty alive? I have written already that inspecting 9M729 is unlikely to be very helpful here. For Russia to agree to show the missile, it would have to be quite certain in advance that the United States will accept that it is a different missile. Otherwise it would just give the U.S. more reasons to accuse it of a treaty violation. The situation is not totally hopeless, but it would require a fairly high level of trust, strong commitment to preserve the treaty, and probably Russia's willingness to take some corrective actions. Alas, all these are in short supply these days.