US military officials announced Wednesday that the Pentagon was “satisfied” that the giant contrail seen Monday evening off the Southern California coast was the product of an airplane flight, not a secret missile launch. Colonel David Lapan, a Pentagon spokesman, told reporters, “There’s no evidence to suggest that it was other than an aircraft.”

While admitting that there was no hard evidence that a plane caused the contrail—the military denies its planes were involved, and no commercial flight has been identified as the source—Lapan added, “this case is closed.”

The conclusion is a purely negative one, based on assurances by the various government agencies that have missile-firing capability that they did not launch a missile during the timeframe the contrail was observed and filmed by a television station traffic helicopter operating out of Los Angeles.

There has been no credible explanation either of the actual phenomena recorded by the KCBS cameraman, since viewed by millions, or of the inability of the vast US military/intelligence apparatus to answer elementary questions about the incident, more than 48 hours after it took place.

Without additional information, it is impossible to accept the official explanation, which echoes the appeals of policemen at a disaster site: “Please keep moving. Nothing to see here.” It is quite possible that the event responsible for creating the contrail is ongoing, and that the official military cover story will be subject to further adjustments.

For the most part, the American media has fallen in behind the Pentagon claim, or else, like the New York Times, said nothing at all about what may be the most serious security event in the United States since the 9/11 attacks.

Hundreds of billions of dollars have been expended in the last decade on homeland security measures, from intrusive passenger inspections to sophisticated equipment to detect and monitor any incoming airplane, ship or other vehicle. Consequently, there is no innocent explanation for the professed inability of myriad agencies—the North American Air Defense Command (NORAD), the Federal Aviation Administration (FAA), the US Northern Command (NORTHCOM), and the Naval Air Warfare Weapons Division—to account for the incident.

It is far more credible to suppose that one or more of these agencies not only detected, but actually organized and carried out some sort of secret test, with or without approval from the highest civilian authorities in Washington. But anyone who challenges the official story—or even raises serious questions—is inevitably branded a proponent of “conspiracy theories.”

The language of the Pentagon statement is remarkably vague. “The Department of Defense, after gathering information over the last 36 hours from within, and other US government agencies, is satisfied that the contrail was likely caused by an aircraft,” Colonel Lapan said.

All US governments organizations “with rocket and missile programs reported no launches, scheduled or inadvertent, during the time period in the area of the reported contrail,” the spokesman said, adding that the military made its determination after looking at multiple “data sources,” but declining to disclose any of them.

Lapan claimed that several planes but no rockets were detected by radar systems on Monday. By Wednesday evening’s broadcast, CBS News was focusing attention on claims that a US Airways jet, Flight 808 from Honolulu to Phoenix, was responsible for the contrail. US Airways said it could not confirm whether its flight, which landed in Phoenix at 7:04 p.m. local time, had been off the coast of southern California at the time of the contrail’s sighting.

The FAA, which operates the nationwide radar system used for civilian air travel, said that it had not been able to determine the location, altitude or trajectory of the contrail. “Without knowing that information, we can’t pinpoint a source,” spokesman Ian Gregor said. “We can’t say where the contrail came from.”

The Naval Air Warfare Center Weapons Division operates the Point Mugu Air Station on the mainland, which is frequently used for weapons launches out over the Pacific. Two other government facilities are nearby: Vandenberg Air Force Base, 30 miles west along the coast, and a Navy facility on San Nicolas Island, which has been used by NASA operations, is the closest to the probable launch site.

There have been several more thoughtful and critical commentaries by security analysts and missile experts who have not bought into the official Pentagon cover story, now generally accepted by the US corporate media.

MIT professor Theodore Postol, a trenchant critic of Pentagon antimissile programs going back to the Reagan administration’s “Star Wars” fantasies, gave an extended rebuttal of the official cover story that an airplane made the contrail.

He told the Christian Science Monitor, “It’s not an aircraft contrail. That I’m confident of. It looks like a big missile, but who knows what a contrail looks like from long range.” He told the newspaper that a review of the video shows twisting movements consistent with maneuvers that long-range ICBMs perform. The contrail “has the spirals you would see in an advanced solid-rocket missile,” he said.

Postol explained that the failure of FAA air-traffic radar to detect the source of the contrail suggested that it was a missile, which would move so fast that it would appear only as a single blip on the screen. On the other hand, he said, NORAD would certainly have detected a missile: “There is no doubt that the North American Air Defense Command early-warning satellites would observe this,” he told the Monitor.

Naval analyst Raymond Pritchett told Wired.com, “When someone makes an unannounced launch what looks to be a ballistic missile 35 miles from the nation’s second largest city (at sea in international waters), and 18 hours later NORAD still doesn’t have any answers at all—that complete lack of information represents a credible threat to national security. If NORAD can’t answer the first and last question, then I believe it is time to question every single penny of ballistic missile defense funding in the defense budget. NORTHCOM needs to start talking about what they do know, rather than leaving the focus on what they don’t know.”

Doug Richardson, the editor of Jane’s Missiles and Rockets, told the Times of London, “It’s a solid propellant missile. You can tell from the efflux [smoke].” He said it could have been a ballistic missile launched from a submarine or an interceptor, the defensive antimissile weapon used by Navy surface ships.

One fact that raises additional questions is an official FAA notice to airmen (NOTAM), issued a few hours before the contrail was filmed by the traffic helicopter. It declares: “The following restrictions are required due to Naval Air Warfare Center Weapons Division activation of W537. In the interest of safety, all non-participating pilots are advised to avoid W537. IFR traffic under ATC jurisdiction should anticipate clearance around W537 …”

W537 is a large swath of the Pacific Ocean extending southwest from Los Angeles through Santa Catalina and others of the Channel Islands. The FAA notice was apparently created at 12:52 p.m. local time Monday (20:52 GMT/UTC), the day of the incident, but was not to take effect until a three-hour period the following day (2 p.m. through 5 p.m. on Tuesday, November 9).