U.S. Defence Department officials say they are unable to explain reports of a missile launch off the Californian Coast on Monday.

The U.S. Defence Department said on Tuesday it was trying to determine if a missile was launched Monday off the coast of Southern California and, if so, who might have fired it.

Spokesmen for the Navy, Air Force, and other military organizations said they were looking into a video posted on the CBS News website that shows an object shooting across the sky and leaving a large contrail, or vapour trail, over the Pacific Ocean.

The video was shot by a KCBS helicopter, the television station said on Tuesday.

“Nobody within the Department of Defence that we’ve reached out to has been able to explain what this contrail is, where it came from,” Pentagon spokesman Col. Dave Lapan said.

Col. Lapan said that “all indications” are that the Department of Defence was not involved within the mystery object, and that the contrail might have been created by something flown by a private company.

Normally any missile test would require notification so that mariners and pilots could be warned or air space closed, but that may not have been done in this case, Col. Lapan said.

“It does seem implausible, and that’s why at this point the operative term is ‘unexplained’,” he said. “Nobody ... within the Department of Defence that we’ve reached out to has been able to explain what this contrail is.”

Missile tests are common off Southern California. Launches are conducted from vessels and platforms on an ocean range west of Point Mugu.

The North American Aerospace Defence Command, or NORAD, issued a statement jointly with the U.S. Northern Command, or NORTHCOM, saying that the contrail was not the result of a foreign military launching a missile. It provided no further details.

“We can confirm that there is no threat to our nation, and from all indications this was not a launch by a foreign military,” the statement said. “We will provide more information as it becomes available.”

NORTHCOM is the U.S. defence command and NORAD is a U.S.—Canadian organization charged with protecting the U.S. from the threat of missiles or hostile aircraft.

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