On 4 April 2017, the Assad regime is alleged to have used chemical weapons on civilians in the Syrian town of Khan Shaykhoun, making it the most deadly such incident since the Ghouta attack in 2013.

The U.S. response to this was firm in that the use of chemical weapons was out of bounds, echoing the Obama administration's referral to the Ghouta attack as having crossed a red line, and in the early hours of April 7, the U.S. retaliated with 59 Tomahawk cruise missiles.

Given this strong position on the use of chemical weapons, detractors would argue that it's a hypocritical position to hold if they themselves had made use of chemical weapons in recent history.

When was the last time the United States employed the use of chemical weapons?

  • 4
    Did you read Wikipedia? en.wikipedia.org/wiki/United_States_chemical_weapons_program . -1 for lack of basic research
    – user4012
    Commented Apr 7, 2017 at 22:15
  • 1
    I did, several times. I'd heard from someone that the US had used chemical weapons, and I wasn't sure that the data in the Wiki article was complete considering that it ended at the Cold War, especially given that it missed the 2012 CWC deadline and still has 20% of its chemical weapons left, so decided to post a question to confirm. Commented Apr 8, 2017 at 1:19
  • 1
    Comments deleted. Please don't post comments which don't offer constructive criticism to the question itself. The discussion about who is responsibility for the chemical weapon incident is not part of it.
    – Philipp
    Commented Apr 10, 2017 at 10:35
  • 2
    @DavidBlomstrom - This is not a forum. Commented Apr 13, 2017 at 4:02
  • 1
    Please guys not again, Ghouta attacks was proven and I mean PROVEN to have been done by al Qaeda, also called US backed "moderate" (tell that to the Syrians) "rebels".
    – Suriya
    Commented Apr 21, 2017 at 15:55

2 Answers 2


The answer to the question hinges on whether you consider "Agent Orange" and other defoliants used in Vietnam to be a chemical weapon.

Agent Orange is toxic to humans, however its primary function is as a herbicide: to kill the forests that the Communist Vietnamese army used as cover. It is claimed that it had a secondary purpose as a chemical weapon. Agent Orange was used throughout "Operation Ranch Hand" which ran from 1961 to 1971.

If you accept the US position that Agent Orange is relatively harmless to people, and was never intended as an antipersonnel weapon, then the last uncontested use of poison gas by the American army was in World War One, in which the US army prepared at least 1400 tonnes of phosgene as well as chlorine and mustard gas. This was a war crime at the time, however, America was not the first belligerent to use chemical warfare in that conflict. All the major adversaries had used gas in WWI.

American law enforcement use various forms of tear gas to disable people non-lethally.

  • 1
    For what it's worth, the US prepared chemical weapons for WWII, and they're still being decommissioned. That's very different from actually using them, though.
    – Bobson
    Commented Apr 7, 2017 at 22:37
  • 6
    Your link about 1400 tons of phosgene seems to be talking about how much was manufactured, not used.
    – Andy
    Commented Apr 8, 2017 at 0:19
  • That's true. However the wikipedia page also mentions the uncontroversial fact that all the major actors in ww1 used poison gas, including the US (though not on the same scale as the British, German or French armies)
    – James K
    Commented Apr 8, 2017 at 6:02
  • It should be noted that the primary use of Agent Orange was to destroy food crops to starve the opponent.
    – user1530
    Commented May 2, 2017 at 1:37

Agent Orange is not relatively harmless to people. It still maims people today in vietnam. I would never take a US claim of why they do things at face value. If we can think up collateral reasons for such uses, you can be sure they are thinking them up also. It seems on the face of it that as far as results were concerned the devastation of Agent Orange as a poison has been more thorough than as a defoliant, a process that was not terribly effective.

The US used gas in Vietnam also, in a tactical role. I think in places like the tunnels. CS gas can kill people in a confined space.

The military also assisted in The gassings at Waco, which was not just a violation at the chemical weapons level, but the restriction at the time against the army being used in civilian maters.

The US also was slow in giving up chemical weapons, and has not taken them out of the arsenals yet, though a plan is in place. While their continued connection with chemical weapons is a bad visual, one can have some sympathy as the us plays in the major leagues, and putting any tool out of use is not always wise. One does trust the US not to lead with chemical weapons as a major element in their warmaking.

On the other hand, the US has so many military capacities, that their ability to inflict misery in retaliation is not particularly limited to any one tool. One of the bad things about gas is the long term chronic pain it causes to survivors. Well welcome to Hiroshima and Nagasaki; or Agent Orange; or depleted uranium dust. Or the US doesn't use conventional terror tactics, but they can calibrate the use of drones in Pakistan or Yemen in such a way as to regress whole populations. A lot more vicious than the odd suicide bomb. So the US can take the high ground on something like chemical warfare when it suits them, and the toolbox is full of so many other tools.

  • 3
    Any references for any of these claims? Commented Apr 8, 2017 at 18:31

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .