How easy/hard is it to start a nuclear war?

A suggestion for more effective deterrance of nuclear war was first made by Roger Fisher in the March 1981 issue of the Bulletin of the Atomic Scientists:

There is a young man, probably a Navy officer, who accompanies the President. This young man has a black attaché case which contains the codes that are needed to fire nuclear weapons. I could see the President at a staff meeting considering nuclear war as an abstract question. He might conclude: “On SIOP Plan One, the decision is affirmative, Communicate the Alpha line XYZ.” Such jargon holds what is involved at a distance.

My suggestion was quite simple: Put that needed code number in a little capsule, and then implant that capsule right next to the heart of a volunteer. The volunteer would carry with him a big, heavy butcher knife as he accompanied the President. If ever the President wanted to fire nuclear weapons, the only way he could do so would be for him first, with his own hands, to kill one human being. The President says, “George, I’m sorry but tens of millions must die.” He has to look at someone and realize what death is—what an innocent death is. Blood on the White House carpet. It’s reality brought home.

When I suggested this to friends in the Pentagon they said, “My God, that’s terrible. Having to kill someone would distort the President’s judgment. He might never push the button.“

Text from an old post at The Nuclear Secrecy Blog, with a hat tip to the staff at Radiolab (which has a somewhat unnerving podcast on this subject).

Reposted from 2016 to add some updated material on how easy or hard it is for someone to start a global nuclear war.  Herewith some excerpts from "How to Start a Nuclear War" in this month's Harper's Magazine:

Serving as a US Air Force launch control officer for intercontinental missiles in the early Seventies, First Lieutenant Bruce Blair figured out how to start a nuclear war and kill a few hundred million people. His unit, stationed in the vast missile fields at Malmstrom Air Force Base, in Montana, oversaw one of four squadrons of Minuteman II ­ICBMs, each missile topped by a W56 thermonuclear warhead with an explosive force of 1.2 megatons—eighty times that of the bomb that destroyed Hiroshima. In theory, the missiles could be fired only by order of the president of the United States, and required mutual cooperation by the two men on duty in each of the launch control centers, of which there were five for each squadron.

In fact, as Blair recounted to me recently, the system could be bypassed with remarkable ease. Safeguards made it difficult, though not impossible, for a two-man crew (of either captains or lieutenants, some straight out of college) in a single launch control center to fire a missile. But, said Blair, “it took only a small conspiracy”—of two people in two separate control centers—to launch the entire squadron of fifty missiles, “sixty megatons targeted at the Soviet Union, China, and North Korea.” (The scheme would first necessitate the “disabling” of the conspirators’ silo crewmates, unless, of course, they, too, were complicit in the operation.) Working in conjunction, the plotters could “jury-rig the system” to send a “vote” by turning keys in their separate launch centers. The three other launch centers might see what was happening, but they would not be able to override the two votes, and the missiles would begin their firing sequence. Even more alarmingly, Blair discovered that if one of the plotters was posted at the particular launch control center in overall command of the squadron, they could together format and transmit a “valid and authentic launch order” for general nuclear war that would immediately launch the entire US strategic nuclear missile force, including a thousand Minuteman and fifty-four Titan missiles, without the possibility of recall. As he put it, “that would get everyone’s attention, for sure.” A more pacifically inclined conspiracy, on the other hand, could effectively disarm the strategic force by formatting and transmitting messages invalidating the presidential launch codes.

When he quit the Air Force in 1974, Blair was haunted by the power that had been within his grasp, andhe resolved to do something about it. But when he started lobbying his former superiors, he was met with indifference and even active hostility. “I got in a fair scrap with the Air Force over it,” he recalled. As Blair well knew, there was supposed to be a system already in place to prevent that type of unilateral launch. The civilian leadership in the Pentagon took comfort in this, not knowing that the Strategic Air Command, which then controlled the Air Force’s nuclear weapons, had quietly neutralized it...

Today, things are different. The nuclear fuse has gotten shorter...

I suggest not reading the article.