In the aftermath of the second Democratic primary debate on July 31, Hawaii Rep. Tulsi Gabbard emerged as the most Googled of all candidates, an indication that her performance (which included a stunning takedown of California Sen. Kamala Harris over her criminal justice record) attracted the attention of many viewers. This heightened level of attention produced blowback, both from Harris, who dismissed Gabbard as “an Assad apologist” (a reference to Syrian President Bashar Assad), and from the mainstream media, typified by CNN’s Chris Cuomo, who alleged that Gabbard—a major in the Hawaiian National Guard, with two tours of duty in the Middle East under her belt—is taking the side of Assad over the U.S. intelligence community and U.N. inspectors when it comes to assigning blame for chemical weapons attacks against Syrian civilians.

“What you are referring to are [sic] cynicism as skepticism that I have expressed, because I’ve served in a war that was caused by people who lied to us, who lied to the American people, who presented false evidence that members of Congress and U.S. senators believed and voted for a war that resulted in the loss of lives of over 4,000 of my brothers and sisters in uniform,” Gabbard replied to Cuomo. “It’s our responsibility as lawmakers and as leaders in this country to make sure that our U.S. military is not being activated and deployed to go to war unless we are certain a) that it serves the best interests of the American people; and b) that that action will actually have a positive impact. The questions I’m raising are based on this experience that I’ve had.”

As someone who challenged the position of the U.S. government regarding Iraq’s weapons of mass destruction programs before the 2003 invasion and occupation of Iraq, I believe that Gabbard’s skepticism over allegations that the Assad government used chemical weapons to attack the towns of Khan Shaykhun in 2017 and Douma in 2018 is well placed.

Gabbard has detailed her concerns about allegations of chemical weapon use in Syria on her campaign website. Her position, and her reliance on the work of Theodore Postol, a Massachusetts Institute of Technology professor who has published critical assessments of both the Khan Shaykhun and Douma incidents, has drawn the ire of many in the mainstream media and elsewhere, including Eliot Higgins, founder of the website Bellingcat, who published a scathing rebuttal of both Postol’s work and Gabbard’s reliance on it.

My purpose here is not to check the veracity of Postol’s research, rebut Higgins’ claims or fact-check Gabbard’s web page. What I will do, as a veteran Marine Corps intelligence officer and experienced weapons inspector, is throw my weight behind Gabbard’s expression of skepticism.

The chemical incident at Douma on April 7, 2018, has been largely debunked—the initial claims regarding the use of the nerve agent sarin have been shown to be false, and evidence has emerged that indicates that a pair of chlorine tanks claimed to have been dropped by helicopters belonging to the Syrian military as weapons were, in fact, manually placed at the scene by opposition forces. There is no doubt that the initial assessment of the situation used by the U.S. government to justify a military strike in response to the allegations regarding Douma was fundamentally flawed, and that Gabbard—alone among all the Democratic presidential hopefuls—was correct to expressed her doubt over its veracity.

More complicated is the incident that occurred at Khan Shaykhun on April 4, 2017. Here, investigators from the Organization for the Prohibition of Chemical Weapons (OPCW) claim to have uncovered evidence that civilians from Khan Shaykhun were exposed to Sarin. The key question surrounding the Khan Shaykhun incident isn’t whether Sarin was used, but rather who used it. The U.S. government and the OPCW have concluded that the Syrian government is responsible for the attack. Postol, Gabbard and I all have concerns over that conclusion.

No independent investigator has been to the site of the Khan Shaykhun incident, including the OPCW investigators who assert Syrian government responsibility. This is a crucial fact that fundamentally affects how data is evaluated. Khan Shaykhun was, at the time of the alleged attack, under the control of opposition forces loyal to the Nusra Front, an al-Qaida offshoot. Several nongovernmental organizations also were present, including the White Helmets, a civil defense/rescue organization, and the Syrian American Medical Society, or SAMS, which provides volunteer medical care in opposition-controlled Syria. Both the White Helmets and SAMS operated under the auspices of the Nusra Front while working in the Khan Shaykhun region. In conducting its investigation, the OPCW relied exclusively upon the White Helmets and SAMS for information regarding the alleged attack, access to alleged victims of the attack for interviews and medical testing, and physical samples alleged to have been removed from the scene of the attack.

This reality is fatal to the credibility of any finding issued by the OPCW. In my 10-plus years as a weapons inspector in both the former Soviet Union and Iraq, I helped write the book on on-site inspections, including developing initial procedures for establishing chain of custody for chemical samples gathered during an inspection. I can assert, without fear of being contradicted, that there can be no formal, legally binding attribution or conclusion made from evidence that lacks an absolute chain of custody from moment of collection to final analysis. This was the case with the United Nations Special Command (UNSCOM) in Iraq, and with the U.N. mission to investigate alleged chemical weapons incidents in Syria. That mission, which operated in Syria from Aug. 19 through Sept. 30, 2013, is on record as rejecting numerous evidentiary materials on the basis of being unable to “independently verify the information received” or “verify the chain of custody for … sampling.”

The OPCW, however, modified its procedures to allow the introduction of both the White Helmets and SAMS into the evidentiary chain of custody, embracing them as a means of information verification even though OPCW investigators were not part of the initiating processes involved in witness selection and screening. This failure to adhere to fundamentals has cast doubt on the credibility of the OPCW’s findings, if for no other reason than that it allowed an al-Qaida-affiliated entity—the Nusra Front—to fundamentally shape its investigation, thereby opening its conclusions to challenge.

Postol and Higgins expend significant effort on discussing the science of sarin; I take a more basic approach to the Khan Shaykhun incident: How did the sarin get there? The OPCW concludes that “a relatively large bomb” delivered “from a medium or high altitude, of between approximately 4,000 and 10,000 m[eters]” is the probable delivery means of the sarin used at Khan Shaykhun. This assessment is highly problematic, especially because it was impossible for the aircraft the OPCW asserts was used to deliver this bomb—a Syrian air force Su-22—to accomplish this task. If it was impossible for the Syrians to drop a chemical bomb on Khan Shaykhun from an aircraft, then the entire episode, as recounted by the OPCW—based upon evidence provided by the Nusra Front, the White Helmet and SAMS—must be viewed as a fabrication.

The OPCW cites radar maps provided by the United States and France that place an Su-22 aircraft over Khan Shaykhun on the morning of April 4, 2017. “The aircraft was depicted as flying in a circular loop pattern in the vicinity of Kafr Zayta and north-east of Khan Shaykhun,” the OPCW report noted. “The map indicated that the closest to Khan Shaykhun that the aircraft had flown had been approximately 5 [kilometers] away.”

This information conforms with Syrian air force logs provided to the OPCW by the Syrian government, as well as a statement provided by a Syrian pilot who flew the Su-22 aircraft on the morning of April 4; the pilot claimed the closest he had flown to Khan Shaykhun was seven to nine kilometers, while carrying out an attack using conventional munitions near the village of Kafr Zayta, situated approximately eight kilometers southwest of Khan Shaykhun.

The OPCW said it consulted with an unnamed “weapons expert” to determine “the confluence of distance and altitude from which it might be possible to hit Khan Shaykhun with an aerial bomb.” The “expert” concluded that “depending on a number of variables such as altitude, speed and the flight path taken, it would be possible for such an aerial bomb to be dropped on the town from the aforementioned distances.” The OPCW did not provide the variables used by the “expert” in making this determination, or an example by which these variables could produce the outcome claimed.

There is a simple reason why it did not—the “expert” is dead wrong.

A briefing provided by a Russian air force officer directly contradicts the OPCW claims that an Su-22 aircraft dropped a bomb on Khan Shaykhun on the morning in question. For the Su-22 to carry out an attack, the Russian officer noted, it must visually acquire the target and, from an altitude of no more than 4,000 meters, fly directly at the target at a speed of 800 to 1,000 kilometers per hour. Based upon these parameters, the release point of a bomb would be between 1,000 and 5,800 meters distant from the target. Even then, the Su-22 would require an additional three to nine kilometers to make a turn away from the target after dropping the bomb. The radar track used by the OPCW shows an Su-22 aircraft flying west of Khan Shaykhun, on a path parallel to the town. The flight path is not consistent with that needed to deliver a bomb on Khan Shaykhun.

While Western “experts” have dismissed the Russian presentation as a charade, I find it credible. As a former aircrew member of a Marine Corps OA-4 Skyhawk light attack aircraft, which possesses performance characteristics similar to that of the Su-22, I have flown air-to-ground strike missions similar to that claimed for Khan Shaykhun. I could fly the flight profile indicated by the U.S. radar track 100 times, and never get a bomb anywhere near the area where the Khan Shaykhun crater in question is located. This point is furthered by the fact that a basic analysis of the crater puts the azimuth of strike nearly perpendicular to the line of flight of the Su-22 when passing west of the town; for a bomb to have been delivered, the aircraft would have had to significantly depart from its flight path, overflying the target, before turning and resuming its course. The radar shows no such deviation. (The “loops” flown by the aircraft north of Khan Shaykhun could likewise never have provided the direction of attack needed to deliver a bomb to the crater in question.) This is the crux of the problem facing the OPCW—it claims that an aerial bomb loaded with sarin was used to strike Khan Shaykhun, and yet the evidence it provides regarding the presence of the sole vector capable of delivering this weapon—the Syrian Su-22—disproves its case.

The tale of the Syrian Su-22 represents both the alpha and omega of the allegations of Syrian government complicity regarding the use of sarin at Khan Shaykhun. One can debate sarin persistency, alternative vectors for agent delivery and other tangential issues until they are blue in the face. But for the Nusra Front, White Helmet and SAMS narrative to be viable, there must have been an attack by a Syrian air force Su-22 that delivered an aerial bomb to the center of Khan Shaykhun. Yet the evidence provided demonstrates conclusively that this could not have occurred. Based upon this reality, everything that follows must be viewed as a “false flag” incident or, as Gabbard’s website notes, “evidence to suggest that the attacks may have been staged by opposition forces for the purpose of drawing the United States and the West deeper into the war.”

“I believe,” Gabbard states on her website, “that we should all carefully look at the evidence before coming to any conclusions as to whether or not al-Qaeda or the Syrian government were responsible for these particular attacks.” That she has done so with a critical eye is not only commendable, but what one would expect from a soldier who seeks to be the commander in chief of the U.S. military.

That the mainstream media continue to attack Gabbard for her stance on Syria and chemical weapons is indicative of the low bar that exists for American journalism today. That President Trump and all the Democratic presidential candidates have failed to display a modicum of intellectual curiosity about what really happened in Douma and Khan Shaykhun should alarm any American who professes to care about issues of war and peace.