Turkey, like much of the Western world, was wrong in its calculations about Syria, and perhaps unwittingly contributed to the chaos. But was Turkey malicious, as well — to the extent of intentionally killing hundreds of defenseless civilians?

That’s what the prize-winning journalist, Seymour Hersh, recently claimed in The London Review of Books, where he presented one of the most intriguing conspiracy theories of late: That a chemical attack on the Damascus suburb Ghouta in August 2013, widely believed to be the work of the Syrian regime, was in fact orchestrated by Turkey. In other words, a war crime that killed some 1,500 civilians was not another monstrosity perpetrated by President Bashar al-Assad, but rather by Mr. Erdogan, who supposedly wanted to create a pretext for an American military intervention in Syria.

This wild argument has probably been well received in Damascus, Tehran and Moscow. Yet, both Washington and Ankara have unequivocally denied it. Moreover, many independent analysts of the Syrian civil war have pointed out flaws in Mr. Hersh’s argument, the bulk of which is based on an unnamed “former intelligence official.”

Mr. Hersh dismissed key facts related to the behavior of the Syrian regime: After the chemical attack on Ghouta, for example, Mr. Assad’s forces kept bombing the area with conventional weapons, and did not allow the United Nations investigation team to examine the area for four days.

With regards to Turkey, Mr. Hersh makes a series of wild claims: Turkey’s national intelligence agency must have first secretly produced sarin gas (while Turkey’s whole military arsenal is conventional and NATO-compliant). Then, it must have obtained Russian-manufactured rockets, modified them to look like the rockets used by Mr. Assad’s armed forces, then secretly smuggled at least a dozen of these two-meter-long missiles into a regime-held part of Damascus, where they were fired into an urban area, willfully killing hundreds. It depicts a Turkish government that is not just very proficient, but also very cruel.