As Hillary Clinton so brilliantly reminded us, next week will mark the 40th anniversary of Bobby Kennedy's assassination in the kitchen of the now-demolished Ambassador Hotel in Los Angeles. The alleged killer, a Palestinian immigrant with the implausible name of Sirhan Sirhan, was sentenced to death by gas chamber until the California legislature had second thoughts and commuted all such punishments to life. As a result, Sirhan still resides in Corcoran prison along with that other bête noire of the 1960s, Charles Manson.

Now I've never been much of a conspiracy theorist, but it doesn't take much of an imagination to understand why an anti-war Democratic candidate such as Kennedy could find himself with some - how can I put this? - “well-trained” enemies in LA. As much as the city is famous for its actors and movie studios, its economy is far more dependent on designing and building new and ingenious ways to kill people.

So was Sirhan a random lunatic, or was he a Manchurian Candidate - an agent of those who feared that Kennedy would bring a halt to the war in Vietnam, thus causing the Pentagon's gravy train to hit the buffers? A new documentary, entitled RFK Must Die, inevitably suggests the latter, citing unexplained bullet holes in the ceiling from a possible second gunmen, and evidence that Sirhan - who kept writing “RFK Must Die” in his diary - was hypnotised. It sounds like the kind of film that Mrs Clinton, with her belief in a “vast right-wing conspiracy”, would enjoy.

Then again, if LA's defence contractors were in the habit of bumping off anyone who cut their funding, her husband would surely be lying under a headstone in Arlington National Cemetery by now. After all, when Bill Clinton took his red pen to Cold War defence budgets in the 1990s, he caused a mini-Armageddon in Southern California. Hundreds of thousands of defence workers left to find work in other states, sending house prices into a slump that almost lasted a decade.

LA's defence industry began to improve only after 9/11, and is now booming like it's 1989. Indeed, California gets about 15 per cent of all Iraq-bloated US defence spending; that works out at as much as $30 billion a year, by my Wikipedia-aided calculations.

But there are big and potentially candidate-endangering differences between now and 1994, as both Mrs Clinton and Barack Obama are no doubt aware. After all, Bill Clinton simply continued Pentagon cuts that were already under way. This time, whoever ends the war in Iraq will be doing it cold - and in an economy that needs all the help it can get. And would you want to be the man or woman responsible for taking $91 billion a year away from hundreds of thousands of the world's most talented killers, many of them veterans, who have access to the very latest in weapons technology? Me neither.

Times Recommends

• Police beg us for food. What hope is there?
• Moral darkness that engulfed Baby P
• More to Advent than cheap chocolate