Why Don’t Dictators Premix Their Chemical Weapons?

Answers to your questions about the news.
Dec. 3 2012 5:52 PM

Why Is Syria Mixing Sarin?

A mini-Explainer on the process of making chemical weapons.

Syrian protesters dance during a demonstration against the regime.
Syrian protesters dance during a demonstration against the Bashar al-Assad regime in Aleppo on Nov. 9.

Photo by Achilleas Zavallis/AFP/Getty Images.

U.S. intelligence sources indicate that the Assad regime is “mixing chemicals” to make sarin gas for use against Syrian rebels. Secretary of State Hillary Clinton said chemical warfare was a “red line,” and the United States would take action if the Assad regime deployed sarin. Why don’t dictators premix their sarin?

Because it’s dangerous, volatile, and corrosive. There are several recipes for sarin, but they all require mixing together some combination of chemicals, such as hydrochloric acid, isopropyl alcohol, hydrogen fluoride, phosphorous trichloride, and difluoromethylphosphonate. Kept separately, some of these chemicals pose minimal threat to handlers or the public. Once mixed, one drop of sarin can kill a person in a matter of minutes. That’s why the United States and other countries have historically maintained the unmixed components of sarin in separate buildings. Sarin is also highly corrosive. The Nazis used solid silver containers to mix sarin, and today’s despots use specialized corrosion-resistant metal alloys to concoct the deadly mixture.

Mixing sarin is actually a rather simple process. In fact, during the 1960s, the United States developed a projectile called the M 687 GB that featured two containers. One container was filled with difluoromethylphosphonate and the other with a combination of isopropyl alcohol and a chemical catalyst called isopropylamine. When the projectile was fired, the launch caused the membrane separating the two substances to break and the spinning action of the flight stirred together the chemicals. By the time the canister reached its destination, the chemical reaction was complete. The United States successfully tested the M 687 with sarin in 1969 and conducted thousands of additional tests with nonlethal chemicals.

The technical challenge for users of sarin is the dispersal. When the Japanese terrorist cult Aum Shinrikyo released sarin on the Tokyo subway in 1995, the attack could have killed hundreds of people. However, the group packaged the chemical in lunchbox-like containers and broke them open with umbrellas. The leaking fluid managed to kill 12 people and hospitalize thousands, but the death toll on the crowded, rush-hour subways would have been far higher had the chemical been aerosolized.

Got a question about today’s news? Ask the Explainer.

Brian Palmer is Slate's chief explainer. He also writes How and Why and Ecologic for the Washington Post. Email him at explainerbrian@gmail.com. Follow him on Twitter.

TODAY IN SLATE

Doublex

Crying Rape

False rape accusations exist, and they are a serious problem.

Scotland Votes to Remain in U.K.

There’s a Way to Keep Ex-Cons Out of Prison That Pays for Itself. Why Don’t More States Use It?

The Music Industry Is Ignoring Some of the Best Black Women Singing R&B

Can Democrats Keep Counting on Republicans to Offend Women as a Campaign Strategy?

Culturebox

Theo’s Joint and Vanessa’s Whiskey

No sitcom did the “Very Special Episode” as well as The Cosby Show.

Television

The Other Huxtable Effect

Thirty years ago, The Cosby Show gave us one of TV’s great feminists.

Cliff Huxtable Explains the World: Five Lessons From TV’s Greatest Dad

Why Television Needs a New Cosby Show Right Now

  News & Politics
The World
Sept. 19 2014 11:36 AM Breaking Up Countries Is Still Hard to Do
  Business
Business Insider
Sept. 19 2014 11:37 AM Why Urban Outfitters and Other Brands Troll Their Customers
  Life
Lexicon Valley
Sept. 19 2014 11:32 AM Why Do Pirates Talk Like That?
  Double X
The XX Factor
Sept. 19 2014 11:33 AM Planned Parenthood Is About to Make It a Lot Easier to Get Birth Control
  Slate Plus
Slate Picks
Sept. 19 2014 12:00 PM What Happened at Slate This Week? The Slatest editor tells us to read well-informed skepticism, media criticism, and more.
  Arts
Behold
Sept. 19 2014 11:51 AM This Is All That’s Left of New York’s Once-Thriving Borscht Belt 
  Technology
Future Tense
Sept. 19 2014 11:40 AM Apple Invented the Perfect Way to Handle Your Giant New Phone
  Health & Science
Bad Astronomy
Sept. 19 2014 11:33 AM The Curious Incident of the Supernova in the Nighttime
  Sports
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.