MIT Professor Theodore Postol, a well known missile expert and former scientific advisor to the U.S. Chief of Naval Operations, analyzed the available evidence of the alleged April 4 Sarin attack on Khan Sheikhun in Syria. He comes to the conclusion that the White House allegations and its report are false. The White House report was not created or vetted by knowledgeable intelligence analysts. This confirms our own analysis published earlier on Moon of Alabama.
Here is Prof. Postol's summary report: The Nerve Agent Attack that Did Not Occur, April 19(pdf, 18 pages).
Previously three preliminary versions of Prof. Postol's analysis were released by him:Moon of Alabama
The Nerve Agent Attack that Did Not Occur - Khan Sheikhun Summary Report by Prof. Postol
The Nerve Agent Attack that Did Not Occur: Analysis of the Times and Locations of Critical Events in the Alleged Nerve Agent Attack at 7 AM on April 4, 2017 in Khan Sheikhoun, Syria