The last time I wrote about the treaty banning "intermediate-range" nuclear missiles was 31 years ago, and I really thought I'd never have to visit that tedious subject again. More fool me.
John Bolton, the ideologically rigid and bad-tempered man whom you send when you don't want a negotiation to succeed, has just been in Moscow to tell the Russians that US President Donald Trump is going to tear up the Intermediate-Range Nuclear Forces (INF) Treaty.
The Russians are just as much to blame for creating the provocation — it's one of those occasions when the idiots are in charge on both sides.
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The INF Treaty, signed by US President Ronald Reagan and Soviet President Mikhail Gorbachev in 1987, bans land-based ballistic or cruise missiles with a range of between 500km and 5500km.
What the Russians have done, it seems, is to take a perfectly legal sea-launched cruise missile, the Kalibr, which has a range of up to 2500km, and put it on a mobile land-based launcher. The Kalibr is a quite useful weapon that can deliver about 500kg of conventional explosives or a nuclear warhead, although it would take at least three hours to reach a target 2500km away (Cruise missiles travel at about the same speed as airliners).
In 2015, Russia made a show of firing 18 Kalibrs (with conventional warheads) at Syrian targets from ships in the Caspian Sea.
Why would the Russians want to put these missiles on land-based launchers, which violates the INF rules?
The only plausible explanation is that there are some Chinese targets that Russia cannot hit with its sea-based cruise missiles (there are no US/Nato targets that cannot be reached by the sea-launched variety).
This is plausible, but not rational. Russia is perfectly capable of reaching those Chinese targets with ballistic missiles, both land- and submarine-launched, that would get to their targets far faster than the new land-based version of the Kalibr cruise missile, called SSC-8 by Nato.
Being able to do the same thing slower hardly justifies the potential political cost of violating the INF Treaty. It may, nevertheless, appeal to the particular branch of the Russian armed forces for inter-service rivalries are as sharp and stupid in Russia as they are in the United States.
From a Western point of view, the Kalibr, while illegal, does not pose any new threat.
The reason the INF Treaty was needed three decades ago was that the Russians were then introducing intermediate-range ballistic missiles that could reach targets in Western Europe within a few minutes of launch.
The border between Nato and Soviet forces was then about 500km closer to Western capitals than it is now, and there were huge tank-heavy armies stacked up on either side of the so-called Iron Curtain.
An ultra-fast Russian strike by nuclear-tipped Kalibrs on Nato army bases and airfields, followed immediately by an all-out ground invasion, could theoretically have succeeded.
The Russians and Americans negotiated instead, and agreed to scrap all their missiles.
Since the US had also deployed some land-based cruise missiles in Europe (the Russians did not), the INF Treaty also banned those. Almost 2700 missiles were destroyed, and the whole issue went away for three decades. It isn't really back now.
There are no massive tank armies ready to roll in Europe any more, and the Cold War is long over.
The details of the Russian-American military balance are of concern mainly to the experts, many of whom make their living by discovering some imbalance or discrepancy that will enable their (military) clients to demand more or newer weapons.
The Russians have broken the rules by developing land-based Kalibr cruise missiles, but they haven't deployed them in meaningful numbers.
They may never do so, because it would not give them any significant strategic advantage.
This was the logic that led former president Barack Obama to protest to the Russians about the new weapon in 2014, but not to abrogate the INF Treaty.
Obama probably assumed adults were still in charge in the Kremlin, and that they were engaged in the same struggle to contain the random enthusiasms of Russian military planners that all US presidents must wage against their Pentagon equivalents. But the White House has a different tenant now.
Gwynne Dyer's new book is Growing Pains: The Future of Democracy (and Work)