President Obama was briefed this morning on an engineering power 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. 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 , E-4B NAOC 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 because the frequencies used to transmit nuclear codes would be interfacing with separate systems, according to officials.



According to the official, engineers believe that a launch control center computer (LCC), responsible for a package of at least five missiles, usually ten of them, 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.



Commanders at the Air Force Base sent warning notices to colleagues at the country's two other nuclear missile command centers, as well as the to the National Military Command Center in Washington. At that point, they did not know what was causing the failure, and they did not know whether other missile systems were experiencing similar symptoms.



According to the official, engineers discovered that similar hardware failures had triggered a similar cascading failure 12 years ago at Minot AFB in North Dakota and Malmstrom AFB in Montana. That piece of hardware is the prime suspect.



The defense official said that there had not been a power failure, though the official acknowledged that that explanation had made its way through public affairs channels. Engineers working on the system presented a draft of their initial findings late this afternoon, the official said.



An administration official, speaking about the president's ability to control nuclear forces, said: "At no time did the president's ability decrease," an administration official said. "



Still, the Chairman of the Joint Chiefs of Staff, Adm. Michael Mullen, was immediately notified on Saturday, and he, in turn, briefed Secretary of Defense Robert Gates.



"We've never had something as big as this happen," a military officer who was briefed on the incident said. Occasionally, one or two might blink out, the officer said, and several warheads are routinely out of service for maintenance. At an extreme, "[w]e can deal with maybe 5, 6, or 7 at a time, but we've never lost complete command and control and functionality of 50 ICBMs."



The military contends that command and control -- "C2" in their parlance -- was not lost.



An Air Force spokesperson, Christy Nolta, said the power failure lasted less than an hour. "There was a temporary interruption and the missiles themselves were always protected by multiple, redundant, safety, security and command and control features. At no time was there any danger to the public," she said.



Another military official said the failure triggered an emergency inspection protocol, and sentries were dispatched to verify in person that all of the missiles were safe and properly protected.



When on alert, the missiles are the property of the U.S. Strategic Command, which controls all nuclear forces. When not on alert status, the missiles are under the control of a subordinate organization, the Global Strike Command,



A White House spokesperson referred questions about the incident to the Office of the Secretary of Defense and to the Air Force. A spokesperson for the Global Strike Command did not immediately respond to questions.



The cause of the failure remains unknown, although it is suspected to be a breach of underground cables deep beneath the base, according to a senior military official.



It is next to impossible for these systems to be hacked, so the military does not believe the incident was caused by malicious actors. A half dozen individual silos were affected by Saturday's failure.



There are about 450 ICBMs in America's nuclear arsenal, some of them bearing multiple warheads. 150 are based at Minot and about 150 are housed at Malmstrom AFB in Montana. The chessboard of nuclear deterrence, a game-theory-like intellectual contraption that dates from the Cold War, is predicated upon those missiles being able to target specific threat locations across the world. If a squadron goes down, that means other missiles have to pick up the slack. The new START treaty would reduce the number of these missiles by 30 percent, but the cuts are predicated upon the health of the current nuclear stockpile, from warhead to delivery system to command and control.



An administration official said that "to make too much out of this would be to sensationalize it. It's not that big of a deal. Everything worked as planned."



Senate Republicans have been pressing Senate Democrats to spend more money ensuring the current strategic nuclear arsenal, which dates to the early 1980s, is ready to go. The treaty requires the vote of two-thirds of the Senate to be ratified.



In 2008, Gates fired the Secretary of the Air Force and its chief of staff after a series of incidents suggested to Gates that the service wasn't taking its nuclear duties seriously enough. At one point, a B-52 bomber flew across the continental U.S. without realizing that its nuclear weapons were "hot."



National Journal's Megan Scully contacted a spokesperson for Sen. Jon Kyl, a top GOP critic of START, who said that "We don't know what happened and why." The spokesperson refused to comment on "media reports."



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 several states.

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

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