Who didn't breathe a sigh of relief when the FBI deduced a proper version of the failed Times Square car bomb would have killed thousands, and nervously joke that it was a good thing Pakistani U.S. citizen Faisal Shahzad didn't listen carefully in al Qaeda Bomb-making 101? But now it turns out that the cheap homemade explosive, left smoking in the back of an SUV in May, was purposely weak, the NY Times reports. Police Commissioner Raymond Kelly, speaking at Washington's Center for National Policy, said Shahzad was afraid that purchasing more potent goods would be noticed by U.S. authorities.

Instead of using more volatile ingredients like ammonium-nitrate-grade fertilizer—a staple of terrorist bombings—Shahzad purchased nonexplosive fertilizer and weak, legally obtainable M-88 fireworks. Paul Browne, the NYPD's chief spokesman, told the Times, "The positive side is it's become more difficult to acquire what once were readily available ingredients for devastating bombs." The Wall Street Journal reports that law enforcement officials apparently have "tripwires" in place, encouraging vendors of the everyday goods needed to concoct bombs to notify them upon any "suspicious behavior or purchases."

Lessons from this ordeal: 1) It's easy to make a crappy DIY bomb; and 2) it's difficult to find people making crappy bombs—Kelly said, "Shahzad is particularly of concern, that type of individual. He is striving to be middle-class, he becomes a U.S. citizen. If you look back, he did some radical things, said some very radical things. But nobody was looking at Shahzad."