A leading weapons academic has claimed that the Khan Sheikhoun nerve agent attack in Syria was staged. Theodore Postol, a [former scientific advisor at the Department of Defense (DoD)], issued a series of three reports in response to the White House's finding that Syrian President Bashar Al-Assad perpetrated the attack on 4 April. Postol said: I have reviewed the [White House's] document carefully, and [it] does not provide any evidence whatsoever that the US government has concrete knowledge that the government of Syria was the source of the chemical attack in Khan Sheikhoun, Syria. "In fact, a main piece of evidence that is cited in the document point to an attack that was executed by individuals on the ground, not from an aircraft, on the morning of 4 April. "My own assessment is that the source [of the sarin release] was very likely tampered with or staged, so no serious conclusion could be made from the photographs cited by the White House." The image Postol refers to is that of a crater containing a shell inside, which is said to have contained the sarin gas. His analysis of the shell suggests that it could not have been dropped from an airplane as the damage of the casing is inconsistent from an aerial explosion. Instead, Postol said it was more likely that an explosive charge was laid upon the shell containing sarin, before being detonated. The implication of Postol's analysis is that [the attack] was carried out by anti-government insurgents as Khan Sheikhoun is in militant-controlled territory of Syria.