What exactly are the strategic advantages of using poison gas?  Militarily, it’s hard to see the temptation; by the standards of modern weaponry, poison gas sure doesn’t seem remarkably cheap or effective.  Politically, moreover, the danger is obvious.  Since almost every major country deplores the use of poison gas, deploying it is a great way to make powerful enemies.

So how would a good game theorist make sense of the decision to use poison gas?  I don’t know, but this 2017 piece by journalist Gwynne Dyer is the best analysis I could find.  Highlights:

When a crime is committed, the likeliest
culprit is the person who benefited from the deed… [W]ho stood to benefit from the
chemical attack in the first place?

There was absolutely no direct military
advantage to be derived from killing 80 civilians with poison gas in
Khan Sheikhoun. The town, located in al-Qaida-controlled territory in
Idlib province, is not near any front line, and it is of no military
significance. The one useful thing that the gas attack might produce,
with an impulsive new president in the White House, was an American
attack on the Syrian regime.

Who would benefit from that? Well, the
rebels obviously would. They have been on the ropes since the Assad
regime reconquered Aleppo in December, and if the warming relationship
between Washington and Moscow resulted in an imposed peace settlement in
Syria, they would lose everything..

Chemical weapons were stored in military
facilities all over Syria, and at one point half the country was under
rebel control…

The results have already been spectacular.
The developing Russian-American alliance in Syria is broken, the
prospect of an imposed peace that sidelines the rebels — indeed, of any
peace at all — has retreated below the horizon…

Just Pro-Putin propaganda?  I think not.  Dyer continues:

But we should also consider the
possibility that Assad actually did order the attack. Why would he do
that? For exactly the same reason: to trigger an American attack on the
Syrian regime. From a policy perspective, that could make perfectly good
sense.

The American attack didn’t really hurt
much, after all, and it has already smashed a developing
Russian-American relationship in Syria that could have ended up imposing
unwelcome conditions on Assad. Indeed, Moscow and Washington might
ultimately have decided that ejecting Assad — though not the entire
regime — from power was an essential part of the peace settlement.

Assad doesn’t want foreigners deciding his
fate, and he doesn’t want a “premature” peace settlement either. He
wants the war to go on long enough for him to reconquer and reunite the
whole country –with Russian help, of course. So use a little poison gas,
and Trump will obligingly over-react. That should end the threat of
U.S.-Russian collaboration in Syria.

Punchline:

Either of these possibilities — a
false-flag attack by al-Qaida or a deliberate provocation by the regime
itself — is quite plausible. What is not remotely believable is the
notion that the stupid and evil Syrian regime just decided that a random
poison gas attack on an unimportant town would be a bit of fun.

Note: Dyer is analyzing last year’s Syrian gas attack, not the latest news…