Click to view images of the improvised rocket assisted mortar launchers and related information.

The explosions in the Sha'ab neighborhood in the Baghdad district of Adhamiyah, which killed 16 civilians and wounded 29 more, have been "misreported," according to the US military. The explosions in the Mahdi Army stronghold were initially reported in the media as a car bomb attack that targeted a police commander. The attack was held up as the largest bombing in Baghdad since mid-March.

But the US military has refuted the reports, saying the explosions were caused by the premature detonation of a Special Groups improvised rocket launching system. The system, which has been described as a flying improvised explosive device, or airborne IED, had received little attention until yesterday’s explosions in Sha’ab.

"There has been a lot of misreporting on yesterday’s event in the Sha’ab neighborhood of Adhamiyah, a district in northeast Baghdad,” said Lieutenant Colonel Steven Stover, the chief Public Affairs Officer for Multinational Division Baghdad, in an e-mail to The Long War Journal. "What I find disconcerting is there have been few corrections. This was not an engagement and these were not Special Groups transporting missiles and mortars in a bongo truck."

The bongo truck was actually the "launch vehicle," according to bomb experts who surveyed the scene. "This was a crude rocket launching system we call an IRAM [improvised rocket assisted mortars] that prematurely detonated causing the other rockets in the truck to catastrophically exploded," Stover said. Two Mahdi Army Special Groups fighters were killed in the subsequent explosions, as well as 16 civilians. Twenty-nine civilians were wounded and 15 buildings were severely damaged.

There were five blast sites, the US military reported. The initial blast occurred at the rocket launcher, while the four other rockets were thrown several hundred meters to the east and detonated. "It is believed the intended targets were US Soldiers at [Forward Operating Base] Callahan and while in the final stages of preparing for the attack, for an unknown reason one rocket prematurely detonated causing the remaining rockets to launch and explode erratically."

The IRAM and the "Lob Bomb"

While the US military related the IRAM explosions in Sha'ab to the April 28 IRAM attacks on Joint Security Station Thawra I in Sadr City and Forward Operating Base Loyalty, there may be two improvised weapons systems at play. Both the JSS Thawra I and the FOB Loyalty attacks were conducted by pulling trucks right outside of the bases' blast walls and firing the improvised rockets into bases. The attack on FOB Loyalty resulted in two soldiers killed and 16 wounded.

The US military said the weapons used in the April 28 attacks had a limited range of between 50 and 150 yards, according to a source familiar with the attack who wishes to remain anonymous. The US military said the range and size of the warhead on the IRAMs is classified.

Based on the images of the launchers used in the April 28 attacks [see slideshow], the IRAM looks to be a large canister, perhaps a propane or fuel tank, filled with explosives and propelled by 107mm rocket booster. These types of improvised weapons -- essentially flying IEDs -- would have a short range and would be highly inaccurate.

Yet the military said the June 3 launcher in Sha'ab may have been pointed at Combat Outpost Callahan, more than 800 yards away from where the launcher exploded. The odds of hitting a US base more than 800 yards away with such a device would be extremely low. The 107mm rocket would be “grossly underpowered” to conduct such a long-range attack, according to a weapons expert.

What is clear is that the devices are using 107mm rocket charges. The US military said these charges are "of Iranian-manufacture." The lot numbers and dates of manufacture show the rocket casings have been manufactured within the past three years.

The rocket casings shown in the images provided by Multinational Forces Iraq are the same type used in the Chinese-made Type 63 towed 107mm Multiple Launch Rocket. The Iranians manufacture this weapons system and the rockets, according to a former US military intelligence analyst familiar with Iranian munitions and weapons systems.

The type of improvised launch system and rocket is not new to warfare. The Irish Republican Army used a similar system to conduct a February 1991 attack on 10 Downing Street, the London office and home of the British prime minister.

DJ Elliott and Bill Ardolino contributed to this article.