How do USA/Russia determine the other's alert (DEFCON) level?

I was watching The Sum of All Fears on cable this weekend, and noticed something: each side (USA and Russia) generally knows when the other side raises their alert status.

How do they do this?

I imagine there are some overt signs associated with each defense level–certain types of bombers/fighters being sent up, subs going to sea, ICBM siloes opening, etc. Is there anything else? A change in radio traffic? Does each side have moles on the other to inform them (or cracked radio codes to intercept the change orders)? Or would the alert status be the sort of information that is shared over the hotline between the two nuclear powers? Or is this just Hollywood BS?

Mostly electronic intelligence and eavesdropping, I would assume. Maybe some human intelligence as well for strategic mobilzations. But this would probably be too slow for minute-to-minute or even some day-to-day stuff.

Such as … ? Are we talking about the USA listening in on uncoded Russian transmissions that say “Raise the Alert Status” ? Or cracked codes/bugs/etc.? Or what?

In the book, the US is eavesdropping on uncoded messages sent by microwave radio, while the USSR has broken the US’s military ciphers and is able to listen in. I can’t remember how it happened in the movie, if it was even dealt with.

Just guessing but even without decoding messages they may be able to determine something is up just by an increase in radio traffic. They also may be able to get intelligence by having spies near various bases watch activity there. Many bases can be peered into fairly easily at least enough to see if things start scrambling around. Add to that watching deployment changes in military forces and I suspect they can add it all up and get a pretty good guess.

Heck…it wouldn’t surprise me if the US told everyone that the DEFCON level has been changed. Why hide it? Part of the point it to telegraph to those pissing you off that you are getting more serious and are more prepared if some shit goes down. Sort of the modern day equivalent of saber rattling.

Yes. We’re watching and listening to them, and they are watching and listening to us. It’s impossible to mobilize your entire military and not send up tons of signals that you’re doing it.

Usually countries will let their neighbors know in advance they’re planning a major exercise, just so they don’t unduly alarm everybody. If your entire military suddenly starts moving, and you haven’t announced a major exercise, all sorts of alarm bells would start going off.

As Whack-a-Mole said, you’d probably want the whole world to know you just raised your alert level anyway.

Back in 1986 when the US bombed Libya, our family knew something big was about to go down about 12-15 hours before it ever hit the media. My sister who lives in the UK was living near a US/NATO base at the time (no affiliation with the base). Living near the base afforded ample opportunity to acclimatize to base operations, including scheduled and unscheduled military exercises.

That night she called home and told us all hell was breaking loose on the base, above and beyond anything she had ever experienced. All aircraft were taxiing out to every available runaway and sitting on the tarmac with engines on high and brakes straining to hold them back. When whatever go signal was given, the base noise exploded in volume, as the planes departed. What really signalled something bad was about to go down was the bombers took the full length of the runways to take off and then climbed ever so low and slowly over the countryside. Never before had this happened.

Any resident spies would have immediately known something was amiss and would have made contact with their home country.

Pay pizza delivery boys a bonus , for any unusal amount of pizzas being delivered

Ballistic missile submarines would sortie , carrier battlegroups would revert to emcon, and it its really serious , fishing trawlers peacefully going about their business would disapear suddenly.

Other than that , radio traffic ,either in the clear from cell phones , or traffic on the mil bands.

Declan

Orbiting satellites could reveal a lot, much more today than many years ago. They could easily detect, even visibly, large scale activity at military bases, etc. If lots of unusual activity at numerous basis was spotted, the other side would know something is up.