Yesterday, via radio, a 48-character long Emergency Action Message (EAM) was transmitted by the U.S. Nuclear Command & Control system.
In the United States military's strategic nuclear weapon nuclear command and control (NC2) system, an Emergency Action Message (EAM) is a preformatted message that directs nuclear-capable forces to execute specific Major Attack Options (MAOs) or Limited Attack Options (LAOs) in a nuclear war.
They are the military commands that the US military chain of command would use to launch a nuclear strike.
Individual countries or specific regions may be included or withheld in the EAM, as specified in the Single Integrated Operational Plan (SIOP).
The SIOP was updated annually until February 2003, when it was replaced by Operations Plan (OPLAN) 8044. Since July 2012, the US nuclear war plan has been OPLAN 8010-12, Strategic Deterrence and Force Employment.
Such messages are usually transmitted amid political crises or on the day of major military operations. Similar EAMs were issued during Russia's invasion of Ukraine and Hamas' October 7th attack on Israel.
The transmissions contain instructions to U.S. nuclear forces in case of various scenarios. Yesterday's transmission was unusually long.
The messages are sent in digital format to nuclear-capable major commands. The messages are then relayed to aircraft that are on alert by the U.S. Strategic Command at Offutt Air Force Base in Omaha, Nebraska, via single-sideband modulation radio transmitters of the High Frequency Global Communications System (formerly known as the Global High Frequency System).
The EAM is relayed to missile-firing nuclear submarines via special transmitters designed for communication with submarines. The transmitters include those designed to operate at Very Low Frequency (VLF).
The submarines pick up the message via special antennas. Nuclear-capable forces will then be expected to carry out an EAM without fail. Crewed bombers may be recalled, but missiles fired from land-based silos or from submarines cannot be recalled.
The messages are encrypted in such a way that no one, anywhere in the world, can figure out what the messages mean, unless they have the printed instruction cards referenced in the message. Thus, only U.S. forces can ever know what the messages actually instruct be done.
