According to a gentleman I know, formerly a high ranking officer in the U.S. military,
THE US IS NOT AT DEFCON 3 – PERIOD. Some in the media reporting on this are biting into a pure propaganda campaign. DEFCON is a defense condition (DEFenseCONdition) relating to the United States posture relating to treats of nuclear war established and maintained by US STRATCOM (United States Strategic Command) and has since then 1950s. Anything and everything about DEFCONs not coming from them is just non-sense. US STRATCOM has not issued a DEFCON 3 status. That is the ONLY measure that matters on this topic.
This article below explains it as a conspiracy, and it is one.
DEFCON is an alert system used by the US military
DEFCON is an alert system used by the US military to indicate the current threat of nuclear war.
The system has five states of alert, increasing in severity from DEFCON 5 – the least severe – to DEFCON 1 – the highest level.
Currently, the levels is understood to be at 5.
But conspiracy theorists have warned the threat has secretly been upgraded two levels to DEFCON 3 – meaning the US could mobilise troops in as little as 15 minutes.