It's not just the number of planes its the variety of types that are flying right now. The level of military cargo has increased dramatically over the last two months. Same for Mil VIP, Special Ops and Reconnaissance planes. But what really tells you how busy they are right now are the multiple refueling planes that have been criss-crossing the country non-stop. And these are only the planes on ADS-B. Preparing for a war that is going to be highly dependent on intelligence, logistics, precision bombing, and special ops.
I remember reading something about an RFP sent out by Darpa for systems to control and spoof the EAS systems of various countries including the US. As I recall it was a capability that they were researching for use in Arab countries during the arab spring. The reason it was making the rounds was due to the requirement for it to work against the US EAS system also which raised a few eyebrows… can't find the original source anymore.
The fact that there were multiple different alert messages that went out should be telling. One very vanilla ballistic missile warning without an issuing agency and the other with specifics such as the issuing agency (US Pacific Command), that there has been a "detection", and instructions for self-protection that are consistent with a Nuclear missile attack.