Pentagon Says 'Mystery Missile' Was a Plane Pentagon doesn't know which plane caused the contrails, but says case is closed.

Nov. 10, 2010 -- The Pentagon has concluded today that the "mystery missile" contrail that startled the country and baffled the Pentagon was caused by a plane and, as far as they're concerned the case is closed.

While the plane has not been identified, military officials made it clear they are not interested in tracking down the aircraft responsible for a visual that sparked worldwide interest.

"With all the information that we have gathered over the last day and a half about this condensation trail (contrail) off the coast of southern California on Monday night, both within the Department of Defense and other U.S. government agencies, we have no evidence to suggest that this was anything other than a contrail caused by an aircraft," Pentagon spokesman Col. David Lapan said.

Lapan said the determination was based on a combination of factors such as "looking at that video and having people determine what the likely cause was…this is how these conditions cause contrails to appear this way, and making sure it wasn't one of our missiles."

The colonel said it took the Pentagon several days to determine the cause of the contrail because, "It's a matter of running down those different leads and talking to those different agencies."

Lapan declined to say whether the military had reviewed satellite imagery to determine whether the contrail had been caused by a missile launch. "Without getting into specifics, we have looked at lots of data sources," he said.

A defense official told ABC News that NORAD and NorthCom's confirmation Tuesday that the contrail did not represent a threat to the U.S. or that a foreign power was responsible for the contrail was based on a review of satellite data.

He dismissed the suggestion that the fact that it took several days to detemine it was a plane and not a missile fired at the U.S. raised questions about the ability to recognize and defend against an attack.

Lapan said there was a difference between the competence in determining a threat to America's airspace, which is what NORAD and NorthCom do, and what happens afterwards in trying to get to the facts after it's been determined that there is no threat.

"Those are two separate things. We said yesterday there was no public threat. What we've been doing since then is try to attribute a cause to the effect that we saw," said Lapan.

Anticipating conspiracy theories, Lapan dismissed the notion that the contrail might be evidence of a secret military project. He noted it was one of the things they looked into when they contacted other federal agencies like the Navy, the Air Force and the Missile Defense Agency.

Lapan said the Pentagon is not interested in tracking down the plane responsible for a story that drew worldwide attention. The U.S. military will not continue to gather specifics such as how far the plane was flying or where it may have been traveling to.

He speculated that perhaps the Federal Aviation Administration might have the capability of making those determinations, but as far as the military's concerned the case is closed.

Experts Weigh in on the Mystery

Michio Kaku, a physics professor at City University of New York and Host of Sci-Fi Science on the Sci-Fi Channel, said on "Good Morning America" today that he had suspected it was created by a plane.

He said the smoking gun was the irregularity in the contrail itself because missiles don't leave a path like that, he said.

Kaku also said that based on the video, "There's no indication of accelerating object in the air," and pilots in the area did not report anything out of the ordinary.

Ivan Orelrich, with Federation of American Scientists and an expert on missile technology, said it could be a jet contrail because if "it's horizontal goes a long, long distance, almost to the horizon, [then] it looks vertical."

He also said that a plane would have had multiple separate contrails that do not seem to appear on the video.

However, Orelrich said he could not be sure about what the video shows because it has characteristics of both a missile launch or perhaps an optical illusion involving a plane's contrail.

Orelrich said he does not believe it could have been a secret missile test.

"If they were going to do that and make it secret, they wouldn't launch it 35 miles from Los Angeles, they would launch it in the South Pacific or something, and so it's difficult to conjure up some story where that makes sense," he said.