Disclaimer from Defcon site

The Defcon Level Warning System is a private intelligence gathering informative organization to keep the public updated on current world events, threats and attempts to assess events and threat levels as accurately as possible when deciding what to set the Defcon level alert status to.

This is not the official government alert status, but a community effort to reflect what the defcon level's alert status is, as accurately as possible at any given time through intel sharing and mutual monitoring of U.S. and global events. The official government alert status is not made available to the public right away. Taken from Defcon Level Warning System: https://www.defconlevel.com/disclaimer.php