Al-Qaeda Pressure Cookers?

The news that the Boston Marathon bombs used conventional pressure cookers led to a flurry of coverage suggesting that this was perhaps a link to Al-Qaeda inspired jihadists.

At the Daily Beast (4/16/13), Eli Lake wrote a piece with this headline:

He was sure to throw in a caveat-this is "far from definitive proof" that the bombing was linked to Al-Qaeda-but the lead pretty clear told the story:

A key component of the bombs used yesterday in the attacks on the Boston Marathon resemble the kind of homemade bomb Al-Qaeda has encouraged English-speaking terrorists to use.

But is that really much of a link at all? Well, the Washington Post's Max Fisher (4/16/13) thought not, writing a piece headlined "Knowledge of Pressure-Cooker Bombs Is Not Limited to Readers of Al-Qaeda's 'Inspire' Magazine":

Yair Rosenberg of Tablet Magazine points out on Twitter that The Anarchist's Cookbook, published in 1971, also included information on how to make them. The book appears to have provided the necessary instructions for at least one such bombing, in 1976 at Grand Central Station. In 1973, police had discovered a similar device in the New York Port Authority building.

Today, there appears to be a miniature subculture of Americans building small pressure-cooker bombs for the exclusive purpose of detonating them harmlessly in empty fields and posting video of the explosion to YouTube.

But the Al-Qaeda link proved irresistible to some in the media. Fox News host Bret Baier explained on the Five (4/16/13):

I mean, listen, you have this Al-Qaeda cookbook about how to make bombs. I mean, this particular type of bomb was described in Inspire magazine, which is Al-Qaeda magazine, of how to make the bomb in kitchen of your mom, was the title of the article. And essentially, it is what Al-Qaeda has used and Al-Qaeda inspired groups have used in different incidents.

Sounds like an open-and-shut case-if you ignore four decades of domestic history, that is.