diff --git a/Acme/Missiles.hs b/Acme/Missiles.hs
--- a/Acme/Missiles.hs
+++ b/Acme/Missiles.hs
@@ -10,15 +10,57 @@
 --     <http://research.microsoft.com/en-us/um/people/simonpj/papers/stm/index.htm#beautiful>
 
 module Acme.Missiles (
-    launchMissiles
+    launchMissiles,
+
+    -- * Launching missiles in the 'STM' monad
+    withMissilesDo,
+    launchMissilesSTM,
 ) where
 
-import Control.Concurrent (forkIO, threadDelay)
-import Foreign.Marshal.Error (void)
+import Control.Concurrent
+import Control.Concurrent.STM
+import Control.Exception (bracket)
+import Control.Monad (forever)
+import System.IO.Unsafe (unsafePerformIO)
 
 -- | Cause serious international side effects.
 launchMissiles :: IO ()
-launchMissiles =
-    void $ forkIO $ do
-        threadDelay 1000000
-        putStrLn "Nuclear launch detected."
+launchMissiles = putStrLn "Nuclear launch detected."
+
+-- | Perform initialization needed to launch missiles in the 'STM' monad.
+withMissilesDo :: IO a -> IO a
+withMissilesDo action =
+        bracket (forkIO doLaunching)
+                killThread
+                (\_ -> action)
+    where
+        doLaunching = forever $ do
+            atomically $ takeTMVar missileCommand
+            launchMissiles
+
+-- | Launch missiles within an 'STM' computation.  Even if the memory
+-- transaction is retried, only one salvo of missiles will be launched.
+--
+-- Example:
+--
+-- >import Acme.Missiles
+-- >import Control.Concurrent
+-- >import Control.Concurrent.STM
+-- >
+-- >main :: IO ()
+-- >main = withMissilesDo $ do
+-- >    xv <- atomically $ newTVar (2 :: Int)
+-- >    yv <- atomically $ newTVar (1 :: Int)
+-- >    atomically $ do
+-- >        x <- readTVar xv
+-- >        y <- readTVar yv
+-- >        if x > y
+-- >            then launchMissilesSTM
+-- >            else return ()
+-- >    threadDelay 100000
+launchMissilesSTM :: STM ()
+launchMissilesSTM = putTMVar missileCommand ()
+
+missileCommand :: TMVar ()
+{-# NOINLINE missileCommand #-}
+missileCommand = unsafePerformIO newEmptyTMVarIO
diff --git a/acme-missiles.cabal b/acme-missiles.cabal
--- a/acme-missiles.cabal
+++ b/acme-missiles.cabal
@@ -1,5 +1,5 @@
 name:                acme-missiles
-version:             0.1.1
+version:             0.2
 synopsis:            Cause serious international side effects.
 description:
     The highly effectful 'launchMissiles' action, as mentioned in /Beautiful concurrency/,
@@ -14,5 +14,5 @@
 
 library
   exposed-modules:     Acme.Missiles
-  build-depends:       base >= 3 && < 5
+  build-depends:       base >= 3 && < 5, stm
   ghc-options:         -Wall