Although most of the discussion about the INF treaty is about the ground-launched cruise missile that Russia is allegedly deploying, the RS-26 ICBM also gets a honorary mention. Both the House and the Senate want the administration to submit a report that should include

(1) a determination whether the RS-26 Ballistic Missile is covered under the New START Treaty or is a violation of the INF Treaty because it has been flight-tested to ranges covered by the INF treaty in more than one warhead configuration; and

(2) if it is determined that the RS-26 is covered under the New START Treaty, a determination whether the Russian Federation

(A) has agreed through the Bilateral Consultative Commission that such a system is limited under the New START central limits; and

(B) has agreed to an exhibition of such a system.

The RS-26 missile, sometimes referred to as Rubezh, is, of course, the missile that appears to be an intermediate-range missile based on the first two stages of RS-24 Yars. It was tested from Plesetsk to Kamchatka in May 2012 and then -- from Kapustin Yar to Sary-Shagan in October 2012, June 2013, and apparently in June 2015 as well.

After that last test the missile was said to be ready for deployment. There was even a plan to begin deployment with the missile division in Irkutsk in 2015. Apparently in anticipation of the upcoming deployment, Russia conduct an exhibition of the missile as it is required by New START. It was supposed to happen at the Votkinsk plant in November 2015.

Then something happened. First, the exhibition was cancelled (in November 2015, probably a few days before it was supposed to happen). At the time it was said that it is moved to 2016, but there were no mention of the exhibition since. Then, deployment of the missile was postponed as well - first to 2016 and then to 2017. Apparently the Rocket Forces planned to conduct a test of RS-26 in 2016. But the test never took place. The plan to deploy two RS-26 regiments (alongside two RS-24 Yars regiments) in Irkutsk appears to remain in place, but there is not much activity there that would suggest that it is going forward.

At first glance, it appears that the question of whether RS-26 is accountable under New START is not particularly controversial. After all, it was tested at 5800 km, which is an ICBM range - Hans Kristensen has a very good discussion of the tests. But it may not be that simple when we turn to the legal status of the missile under New START.

The key word here is "prototype". In New START, a prototype is a missile that has not been tested more than 20 times and that has not been deployed:

The term "prototype" means, for ICBMs or SLBMs, an ICBM or SLBM of a new type, no more than 20 missiles of which have been launched, and no launchers of missiles of which have been deployed.

It is most likely that for the purposes of the treaty RS-26 was declared as prototype of a new ICBM. And as long as a missile is a prototype, it does not really have any characteristics. As long as missile is under development, everything can be in flux - the diameter, length, the number of warheads (or the number of stages, for that matter). These became fixed in the treaty data exchange only when the missile is officially declared to be a new type of ICBM. Until that moment these characteristics do not exist for the purposes of the treaty. This is how Russia was able to test RS-24 Yars, which is very much a MIRVed Topol-M, in 2007, while START was still in force, even though the START Treaty prohibited MIRVing existing single-warhead missiles.

Does this apply to the demonstrated range? This is an intriguing possibility. New START does not seem to say this directly, but one can make a good argument that as long as a missile is a prototype, its demonstrated range should not count. Which means that as far as the New START is concerned, RS-26 may not be an ICBM. In fact, it may not be a missile at all - Russia could simply notify the United States that it cancels development of this prototype. Is is an INF-range missile then? Not necessarily, since Russia can argue that it was tested to a range of more than 5500 km. Unless RS-26 loses its prototype status, we cannot really say anything definitive about the missile. It's almost like a Schrödinger missile - unless you open the box it is neither ICBM nor IRBM.

So, the question asked by Congress is not as silly as it may seem - it appears to be possible that Russia can claim that RS-26 is not covered under the New START treaty. It would be interesting to read that report. Among other things, it would be good to know what was the formal status of that exhibition that Russia planned to hold in November 2015. Did it amount to an admission of the ICBM status of RS-26? I hope someone who knows details can help clarify this. My guess is that since the Obama administration did not include RS-26 in the compliance report, there is at least an understanding with Russia that RS-26 is an ICBM. But who knows...

Legal issues aside, the main reason Congress is agitated about RS-26 is that does appear to be an intermediate-range missile in the guise of an ICBM. According to that argument, since it was tested mostly at 2000 km range, it is an intermediate-range missile that violates the INF treaty. Well, it all depends on whether RS-26 is covered under New START as an ICBM. If it is, it will count against the New START limits, so there is no violation there. In fact, most Russian ICBMs can be launched at INF range. Alexandr Stukalin kindly shared with me this very interesting table that he compiled some time ago:

The table clearly shows that virtually all ICBMs have minimum ranges well below the 5,500 km INF limit. I doubt it occurred to anyone to suspect that SS-19 is a violation of the INF Treaty. Yes, it is true that SS-19 has not been tested at 1,000 km. But other missiles have - as Alexander noted, nobody is concerned that SS-25/Topol is regularly launched from Kapustin Yar to Sary-Shagan, just as RS-26 -- see, for example, the launch in December 2015.

It well may be that RS-26 will be formally declared as ICBM and will become just another missile in this category of "intermediate-range ICBMs." Ot it may turn out differently. I wouldn't say I am particularly optimistic at this point, but we will see.