U.S. officials are scrambling to explain a possible missile launch off the coast of Los Angeles, but a day after a vapor trail was caught on tape the incident remains a mystery, a Pentagon spokesman said on Tuesday.

The apparent missile launch was caught on tape by a KCBS news helicopter on Monday evening. Video shows a billowing contrail apparently rising from the water about 35 miles west of Los Angeles and north of Catalina Island. It is not clear whether it comes from land or sea.

"So far we've come up empty with any explanation," Colonel David Lapan told reporters. "We're talking to other parts of the U.S. government. We're doing everything we can to try to figure out if anybody has any knowledge of what this event may have been."

I imagine they are scrambling, at this late point. To read the rest of the article, click here.