50 ICBMs Accidentally Shut Down
Marc Ambinder reports:
President Obama was briefed this morning on an engineering failure at F.E. Warren Air Force Base in Wyoming that took 50 nuclear intercontinental ballistic missiles (ICBMs), one-ninth of the U.S. missile stockpile, temporarily offline on Saturday.
The base is a main locus of the United States' strategic nuclear forces. The 90th Missile Wing, headquartered there, controls 150 Minuteman III intercontinental ballistic nuclear missiles. They're on full-time alert and are housed in a variety of bunkers across the base.
On Saturday morning, according to people briefed on what happened, a squadron of ICBMs suddenly dropped down into what's known as "LF Down" status, meaning that the missileers in their bunkers could no longer communicate with the missiles themselves. LF Down status also means that various security protocols built into the missile delivery system, like intrusion alarms and warhead separation alarms, were offline. In LF Down status, the missiles are still technically launch-able, but they can only be controlled by an airborne command and control platform like the Boeing E-6 NAOC "Kneecap" aircraft, or perhaps the TACAMO fleet, which is primarily used to communicate with nuclear submarines. Had the country been placed on a higher state of nuclear alert, those platforms would be operating automatically.
According to the official, engineers believe that a launch control center computer (LCC), responsible for a package of five missiles, began to "ping" out of sequence, resulting in a surge of "noise" through the system. The LCCs interrogate each missile in sequence, so if they begin to send signals out when they're not supposed to, receivers on the missiles themselves will notice this and send out error codes.
Since LCCs ping out of sequence on occasion, missileers tried quick fixes. But as more and more missiles began to display error settings, they decided to take off-line all five LCCs that the malfunctioning center was connected to. That left 50 missiles in the dark. The missileers then restarted one of the LCCs, which began to normally interrogate the missile transceiver. Three other LCCs were successfully restarted. The suspect LCC remains off-line.
