BERLIN — A series of revelations about the rocket believed to have delivered poison sarin gas to a Damascus suburb last summer are challenging American intelligence assumptions about that attack and suggest that the case U.S. officials initially made for retaliatory military action was flawed.A team of security and arms experts, meeting this week in Washington to discuss the matter, has concluded that the range of the rocket that delivered sarin in the largest attack that night was too short for the device to have been fired from the Syrian government positions where the Obama administration insists they originated.Separately, international weapons experts are puzzling over why the rocket in question an improvised 330mm to 350mm rocket equipped with a large receptacle on its nose to hold chemicals reportedly did not appear in the Syrian governments declaration of its arsenal to the Organization for the Prohibition of Chemical Weapons and apparently was not uncovered by OPCW inspectors who believe theyve destroyed Syrias ability to deliver a chemical attack.Neither development proves decisively that Syrian government forces did not fire the chemicals that killed hundreds of Syrians in the early morning hours of Aug. 21. U.S. officials continue to insist that the case for Syrian government responsibility for the attack in East Ghouta is stronger than any suggestion of rebel involvement, while experts say it is possible Syria left the rockets out of its chemical weapons declaration simply to make certain it could not be tied to the attack.That failure to declare can mean different things, said Ralf Trapp, an original member of the Organization for the Prohibition of Chemical Weapons and a former secretary of the groups scientific advisory board. It can mean the Syrian government doesnt have them, or that they are hiding them.In Washington, the Office of the Director of National Intelligence said its assertion of Syrian government responsibility remains unchanged. The body of information used to make the assessment regarding the August 21 attack included intelligence pertaining to the regimes preparations for this attack and its means of delivery, multiple streams of intelligence about the attack itself and its effect, our post-attack observations, and the differences between the capabilities of the regime and the opposition. That assessment made clear that the opposition had not used chemical weapons in Syria, it said Wednesday in an email.But the authors of a report released Wednesday said that their study of the rockets design, its likely payload and its possible trajectories show that it would have been impossible for the rocket to have been fired from inside areas controlled by the government of Syrian President Bashar Assad.In the report, titled Possible Implications of Faulty U.S. Technical Intelligence, Richard Lloyd, a former United Nations weapons inspector, and Theodore Postol, a professor of science, technology and national security policy at the Massachusetts Institute of Technology, argue that the question about the rockets range indicates a major weakness in the case for military action initially pressed by Obama administration officials. The administration eventually withdrew its request for congressional authorization for a military strike after Syria agreed to submit to the Chemical Weapons Convention, which bans the weapons. Polls showed overwhelming public opposition to a military strike, however, and it was doubtful Congress would have authorized an attack.Lloyd and Postols report is the most recent installment in a months-long debate among rocket and weapons experts, much of it carried out in detailed papers posted on the Internet, about the nature of the munitions used in the Aug. 21 attack on rebel-controlled suburbs of Damascus. The reports authors admit that they deal only with one area of the attacks, the eastern suburb of Zamalka, where the largest quantity of sarin was released that night. They acknowledge that smaller rockets likely used in areas southwest of the capital could have come from government-controlled territory. Relying on mathematical projections about the likely force of the rocket and noting that its design some have described it as a trash can on a stick would have made it awkward in flight, Lloyd and Postol conclude that the rocket likely had a maximum range of 2 kilometers, or just more than 1.2 miles. That range, the report explains in detail, means the rockets could not have come from land controlled by the Syrian government.To emphasize their point, the authors used a map produced by the White House that showed which areas were under government and rebel control on Aug. 21 and where the chemical weapons attack occurred. Drawing circles around Zamalka to show the range from which the rocket could have come, the authors conclude that all of the likely launching points were in rebel-held areas or areas that were in dispute. The area securely in government hands was miles from the possible launch zones.In an interview, Postol said that a basic analysis of the weapon some also have described as a looking like a push pop, a fat cylinder filled with sarin atop a thin stick that holds the engine would have shown that it wasnt capable of flying the 6 miles from the center of the Syrian government-controlled part of Damascus to the point of impact in the suburbs, or even the 3.6 miles from the edges of government-controlled ground. He questioned whether U.S. intelligence officials had actually analyzed the improbability of a rocket with such a non-aerodynamic design traveling so far before Secretary of State John Kerry declared on Sept. 3 that we are certain that none of the opposition has the weapons or capacity to effect a strike of this scale particularly from the heart of regime territory.I honestly have no idea what happened, Postol said. My view when I started this process was that it couldnt be anything but the Syrian government behind the attack. But now Im not sure of anything. The administration narrative was not even close to reality. Our intelligence cannot possibly be correct.Lloyd, who has spent the past half-year studying the weapons and capabilities in the Syrian conflict, disputed the assumption that the rebels are less capable of making rockets than the Syrian military.The Syrian rebels most definitely have the ability to make these weapons, he said. I think they might have more ability than the Syrian government.Both said they were not making a case that the rebels were behind the attack, just that a case for military action was made without even a basic understanding of what might have happened.For instance, they said that Kerrys insistence that U.S. satellite images had shown the impact points of the chemical weapons was unlikely to be true. The charges that detonate chemical weapons are generally so small, they said, that their detonations would not be visible in a satellite image.The report also raised questions whether the Obama administration misused intelligence information in a way similar to the administration of President George W. Bush in the run-up to the 2003 invasion of Iraq. Then, U.S. officials insisted that Iraqi dictator Saddam Hussein had an active program to develop weapons of mass destruction. Subsequent inspections turned up no such program or weapons.What, exactly, are we spending all this money on intelligence for? Postol asked.As for the failure of the Syrians to list the rocket in its chemical weapons inventory, experts are undecided on what it means and leery about discussing it in public.A spokeswoman for the Organization for the Prohibition of Chemical Weapons in Damascus declined to comment on what was listed in the declaration. It would violate the Chemical Weapons Convention for anyone who has read the declaration its distributed to all nations that have joined the treaty to reveal its contents.Knowledgeable experts said discussion of the apparent omission has been muted because no one wants to say anything that would disrupt what appears to have been the successful dismantling of Syrias chemical weapons program.Some say they are worried that the failure to declare one delivery system may also mean that other items went undeclared.The most likely explanation for some of the delivery systems not showing up on the chemical declaration is that Assad doesnt want to incriminate himself or his regime, said Daryl Kimball, the executive director of the Arms Control Association. Jonathan S. Landay in Damascus, Syria, and Hannah Allam and Anita Kumar in Washington contributed to this report.