Blowback is "a term invented by the Central Intelligence Agency to describe the unintended consequences of policies kept secret from the American people. Chalmers Johnson’s excellent book, Blowback: The Costs and Consequences of American Empire [Owl Books, 2000, ISBN 0805075593], helped popularize the term. Originally intended for internal use only, blowback increasingly characterizes global reaction to Bush administration policies in and out of the Middle East." 
As it "refers to the unintended results of American actions abroad," in his "incisive and controversial book, Chalmers Johnson lays out in vivid detail the dangers faced by our overextended empire, which insists on projecting its military power to every corner of the earth and using American capital and markets to force global economic integration on its own terms. From a case of rape by U.S. servicemen in Okinawa to our role in Asia’s financial crisis, from our early support for Saddam Hussein to our conduct in the Balkans, Johnson reveals the ways in which our misguided policies are planting the seeds of future disaster."
Blowback is also the mess that lands on a shooter when firing a gun into someone at close range. The term is used as metaphor for situations in which one party has done violence to another in some way and then suffers consequences from their own violence.
The term recently has been applied to the growth of an Al Qaeda guerilla warfare network from U.S. insurgency training efforts of Mujahideen in Afghanistan. When powerful governments train insurgents to aid in the government's campaign against another, sometimes the trained insurgents use their skills for other purposes, including to attack the government that trained them.
Foreign Affairs commentator Eric Margolis noted prior to Nov. 2001 the continuing cycle of American political involvement in the Middle East. He points out that in nearly every decade since the mid-fifties, a president of the United States has faced a challenge of a Muslim peril, an Arab or Muslim bogeyman that is everywhere and nowhere--Nasser, Khomeini, Khadafy, Saddam, and, now, bin Laden. And every time, the results have been the same: U.S. demonizes this single man, only to watch him grow into a popular hero of the Arab masses--the Arabic or Islamic David that dares to stand up and confront the U.S. oil dominion over the Arab world and the economic and political distortion that the US leaves in its wake. 
War in Iraq
From the July 23, 2003, edition of World in Conflict comes Paul deArmond's (aka "Warbaby") "Iraqi National Congress and Blowback"; deArmond writes:
- "What has not been widely discussed is the central role the Iraqi National Congress (INC) played in the road to war -- not as puppet but instigator. The role of the INC in generating unreliable 'intelligence' on Iraqi weapons of mass destruction (WMD -- meaning nuclear, chemical and biological weapons) has been mentioned in passing in the media since the occupation started to go sour. Once the investigations move beyond the ability of some as-yet unidentified foreign operation to plant childishly crude forgeries in the State of the Union 2003 address, the INC's steady stream of questionable intelligence will deserve more scrutiny.
- "And that's where the afore-mentioned list of bogus assumptions in the Bush war plan become very interesting. You see, all of them trace back to a single source. If you guessed the Iraqi National Congress, you win the exploding cigar!"
The recent revelations regarding Ahmed Chalabi and his "fall from grace" make deArmond's observations nearly clairvoyant.
Orcinus, who posted deArmond's 2003 article June 1, 2004, comments: "His conclusions back then, in particular, seem especially relevant:
- "The White House allowed the false information to circulate through the echo chamber of the media. The hawks made baseless allegations that would move America closer to war, the INC dutifully provided the 'intelligence' selected to reinforce their masters' views, the media uncritically echoed the leaks and statements by 'unnamed officials' -- and the public was manipulated.
- "The intentions of the parties involved may be arguable, but the effect is indistinguishable from psychological warfare against the national interest.
- "The debate over whether the misinformation was a product of intentional deceit or incompetent gullibility misses one important point: the United States government needs to be protected from bad intelligence and particularly needs to be defended against external manipulation. In this case, the counter-intelligence apparatus failed to defend the integrity of the intelligence process and the country has been manipulated by misinformation disguised as 'intelligence.'"
Also, this describes the backward action of some submachine guns, ie, Sterling-Patchett MK IX; and the older Sterling-Enfield (Sten) submachine guns of all marks.