Stars and Stripes reports:

"VBIEDs are not a major threat against coalition forces in Baghdad right now," RisCassi said in a recent interview.

Indeed, according to figures released by the military in October, car bomb attacks throughout the country have gone down 65 percent since the "surge" in June.

You don't want to jinx it, but the first half of December has seen remarkably light casualties among U.S. forces. As of today, icasualties.org only counts seven U.S. servicemen killed in Iraq for December, and of those, only five were killed by hostile fire. If the trend holds, obviously a big if, it could be the lowest casualty total for U.S. troops of any month since the war started. Unfortunately, civilian casualties are on pace for a total of a little under 500--right around where they were last month, but down more than 80 percent from their peak in February. And of course, vehicle borne explosives are al Qaeda's preferred method for generating mass casualty attacks. Still, one soldier explains that the recent drop hasn't allowed U.S. troops to let down their guard:

"You are more relaxed around vehicles but just because we haven't had any doesn't mean it's safe," he said. "Guys still need to treat every car like it is a threat because you never really know."

But the troops largely attribute the decline to tips from locals, which creates a sort of positive feedback loop where improved security leads to greater trust, more tips, and further gains in security.