By now, you’ve probably seen the video footage of a strange, missile-like object arcing across the orange California sky. For the past two days, experts have been debating what it was. While some speculate the object could have been a rocket—even a Chinese submarine-launched test—federal officials, including the military at the North American Aerospace Defense Command in Colorado Springs, remain befuddled. “While there is nothing at this time that leads the Department of Defense to believe this is a missile launch, the department and other U.S. government agencies with expertise in aviation and space continue to look into the condensation trail seen and reported off the coast of Southern California on Monday evening,” Pentagon spokesman Colonel Dave Lapan tells The Washington Times.

The bi-national, U.S.-Canadian NORAD, which works closely with U.S. Northern Command on Peterson Air Force Base in the Springs, uses a worldwide system of sensors to detect missile launches aimed at North America, but they uncovered none. And no foreign sea crafts were detected nearby. One leading theory is that the object, filmed by a local news station’s helicopter, was actually a plane, Britain’s Telegraph explains.