The forerunner of the internet, developed by the U.S. Defense Department.

Did the kill switch really exist?

Yes — as a command to disable key routing functions in emergencies.

Do modern networks have a kill switch?

Not exactly — but governments can shut off national internet access in some countries.

The Internet Once Had a Kill Switch — And It Was Almost Used

Before the World Wide Web, there was ARPANET — the U.S. government-funded project that laid the foundation for the modern internet. In its early days, the network was small and experimental… and it had a kill switch.

Engineers built ARPANET with a command that could shut down the entire system instantly — a safeguard in case of catastrophic failure, hacking, or misuse. The command was secret, restricted to a few administrators, and never meant to be used lightly.

In 1980, a software bug caused widespread instability across ARPANET. Panic spread. Some debated using the kill command, fearing the issue could spiral out of control. But cooler heads prevailed, and the network survived.

The concept of a “kill switch” still surfaces today — in debates about government power over communications, cybersecurity, and emergency response systems.

So yes, the internet once had a “stop” button. And for a brief moment, someone nearly pressed it.