Flare.

This is coolbert:

Courtesy the "Watts Up With That" Internet web site.

"Disclosure: Solar flares in 1967 almost started World War III"

"1967 solar storm nearly took US to brink of war"

"From AGU WASHINGTON, DC — A solar storm that jammed radar and radio communications at the height of the Cold War could have led to a disastrous military conflict if not for the U.S. Air Force’s budding efforts to monitor the sun’s activity, a new study finds."

"On May 23, 1967, the Air Force prepared aircraft for war, thinking the nation’s surveillance radars in polar regions were being jammed by the Soviet Union. Just in time, military space weather forecasters conveyed information about the solar storm’s potential to disrupt radar and radio communications. The planes remained on the ground and the U.S. avoided a potential nuclear weapon exchange with the Soviet Union, according to the new research."

BMEWS JAMMED BY SOLAR FLARE. BALLISTIC MISSILE  EARLY WARNING RADAR [CLEAR ALASKA, FLYINGDALE MOORS AND THULE GREENLAND ] SYSTEM THE MISSION OF WHICH WAS TO DETECT MISSILES WITH NUCLEAR WARHEAD AS LAUNCHED FROM SIBERIA OVER THE NORTH POLE TOWARD THE USA!

JAMMING AS THOUGHT TO BE A PROCESS OF THE SOVIET INTENTIONAL A PRELUDE TO NUCLEAR ATTACK ON THE USA.

Things nearly got hot that day but thankfully cooler heads prevailed.

See also another instance during the Cold War when magnetic disturbance with a solar origin caused problems for the U.S. military:

https://militaryanalysis.blogspot.com/2018/11/magnetic.html

coolbert.