If you read the WND article carefully, all the questions are asked and answered. No missile, definitely not a DOD missile, every possible source of US launch was checked. How WND makes this into "Officials refuse to explain launch warning where contrail filmed" and further infers it was a US launch (hence the "U.S. warned people to avoid mystery missile zone" headline) is beyond sloppy.
There's just no there, there in the article itself.