One of the worst, sometimes tragic consequences of an action is the “boomerang,” or “backfire” effect: A miscalculation that recoils on its maker.
Iraq is nothing but miscalculation after miscalculation with a lots of boomerang.

Although Shiite cleric Muqtada al-Sadr, whose Mehdi Army Iraqi security forces, and now US and UK GIs, have been battling in Basra and Baghdad all this week, issued a statement this morning for his fighters to cease fire: “We announce our disavowal from anyone who carries weapons and targets government institutions, charities and political party offices,” said the statement that was distributed across the country and posted on Web sites linked to his movement.
There was, however, one, big caveat: Sadr demanded the Iraqi central government give his supporters amnesty and to release all those held.
And this, Iraqi Prime Minister Nouri al-Maliki will not do — the boomerang will keep boomeranging.

Yesterday:

BAGHDAD — Anti-American Shiite militia leader Muqtada al-Sadr ordered his followers Saturday to defy government orders to surrender their weapons, as U.S. jets struck Shiite extremists near Basra to bolster a faltering Iraqi offensive against gunmen in the city.
Prime Minister Nouri al-Maliki acknowledged he may have miscalculated by failing to foresee the strong backlash that his offensive, which began Tuesday, provoked in areas of Baghdad and other cities where Shiite militias wield power.
The U.S. Embassy tightened its security measures, ordering all staff to use armored vehicles for all travel in the Green Zone and to sleep in reinforced buildings until further notice after six days of rocket and mortar attacks that left two Americans dead.
British ground troops, who controlled the city until handing it over to the Iraqis last December, also joined the battle for Basra, firing artillery Saturday for the first time in support of Iraqi forces.
…
Gunfire and explosions were heard late Saturday in Sadr City, the Baghdad stronghold of al-Sadr’s Mahdi Army militia.
…
But a defiant al-Sadr called on his followers Saturday to ignore the order, saying that his Mahdi Army would turn in its weapons only to a government that can “get the occupier out of Iraq,” referring to the Americans.
The order was made public by Haidar al-Jabiri, a member of the influential political commission of the Sadrist movement.
Al-Sadr, in an interview aired Saturday by Al-Jazeera television, said his Mahdi Army was capable of “liberating Iraq” and maintained al-Maliki’s government was as “distant” from the people as Saddam Hussein’s.

If that wasn’t enough:

Meanwhile, Iraqi officials said they had received a phone call from Tahseen Sheikhly, the high-profile civilian spokesman for the Baghdad security operation, who was seized by gunmen two days earlier from at his home in a Shiite area of the capital.
An Iraqi-owned satellite television station, Sharqiya, broadcast what it said was a tape of the conversation, in which a man identifying himself as Sheikhly said he was being held “with a group of officers” at an unknown location.
“Our release depends on the withdrawal of al-Maliki from Basra and the easing of the military operations against the Sadrists in all provinces,” he said. “We appeal to the prime minister and the Iraqi government to work with the Sadrist movement, which represents the popular base of society.”
— telegraph.com.uk, (3/28/08)

And Maliki just can’t keep his mouth shut.

“We used to talk about al Qaeda. Unfortunately it seems there are some among us who are worse than al Qaeda,” Maliki said in a televised meeting with tribal leaders in Basra, where he has personally overseen the crackdown since Tuesday.
— Reuters, (3/29/08)

The greatest miscalculations with the greatest boomerang effect has, of course, come from the US:

• “It is unknowable how long that conflict [the war in Iraq] will last. It could last six days, six weeks. I doubt six months.”
  — Then Secretary of Defense Donal Rumsfeld, February, 2003
• “There has been a good deal of comment—some of it quite outlandish—about what our postwar requirements might be in Iraq. Some of the higher end predictions we have been hearing recently, such as the notion that it will take several hundred thousand U.S. troops to provide stability in post-Saddam Iraq, are wildly off the mark. It is hard to conceive that it would take more forces to provide stability in post-Saddam Iraq than it would take to conduct the war itself and to secure the surrender of Saddam’s security forces and his army—hard to imagine.”
  — Then Deputy Secretary of Defense Paul Wolfowitz, House Budget Committee testimony on Iraq, Feb. 27, 2003
• “I think things have gotten so bad inside Iraq, from the standpoint of the Iraqi people, my belief is we will, in fact, be greeted as liberators.”
  — Vice President Dick Cheney, March 16 2003

And, of course, Decider George:

• “Major combat operations in Iraq have ended. In the battle of Iraq, the United States and our allies have prevailed.”
  — speaking underneath a “Mission Accomplished” banner aboard the USS Abraham Lincoln, May 1, 2003
• “My answer is bring them on.”
  — on Iraqi insurgents attacking U.S. forces, Washington, D.C., July 3, 2003

The biggest miscalculation, however, was by the US voter in November 2004.