Scott Glenn!

It kind of reminds me of SPECIAL BULLETIN, same format, although that one was about nuclear terrorism in Charleston SC, not full-on thermonuclear war.

SPECIAL BULLETIN also has an ironic timing twist story: it won "Outstanding Drama Special" at the 1983 Emmys, broadcast on September 25th, 1983. Meanwhile, in Russia (where it was already the morning of the 26th), some high altitude clouds were causing some confusion at the Serpukhov-15 bunker, the western command center for the OKO satellites which give early warning for American missile launches. Seemed the clouds somehow showed up as the Americans launching 4 missiles towards Russia. Were it not for lieutenant colonel Stanislav Petrov correctly deducing that the United States would not launch only 4 ICBM's as a first strike, the live broadcast of the 1983 Emmys on NBC would have been interrupted by a real life Special Bulletin, one where they wouldn't exactly have been able to resume normal broadcasting afterwards as the Pasadena Civic Auditorium where the Emmys were held would have been fiery radioactive rubble along with most of the rest of the Los Angeles area (and most other US cities and other strategic targets).

1:24:19 I'm not sure if this is the very first fictionalized "We interrupt this program. This is a national emergency. Important instructions will follow." Emergency Broadcast System warning ever recorded... three decades later, there are whole Youtube channels dedicated to fictional EBS warnings for those of us spergs who have a sick fascination with what the last few minutes of television we might ever see might be like.