This morning's National Public Radio piece about Mexico's Los Zetas drug cartel ends with a jarring quote from Tony Zavaleta, the interim provost of a Texas university that was hit by gunfire this month when a firefight between Mexican soldiers and drug traffickers sent stray bullets across the Rio Grande and onto American soil: "I'm not going to say it's becoming normal, or that we're going to take it cavalierly," Zavaleta told NPR. "But it's not that unusual anymore."

Deserters from the Mexican army formed Las Zetas.

The U.S. Drug Enforcement Administration's chief of intelligence, Anthony Placido, told NPR that the cartel those deserters built is "every bit as ferocious and as capable as a military force as some of the rumors believe them to be. ... They're heavily armed with .50-caliber sniper riles and heavy military-grade ordnance."

So Las Zetas is no mere drug gang -- not just a gang, not just involved in trafficking drugs.

The NPR piece includes the stunner that "Mexican authorities reported that the Zetas used false import documents to smuggle at least $46 million worth of oil in tankers for sale to U.S. refineries."

The police chief of one Mexican town in Zeta territory went pale when NPR's John Burnett asked him about the drug cartel's prevalence. The police chief, whose predecessor was gunned down on his very first day as chief, told NPR, "I can't tell you if they exist or not. You read a lot about them, but I can't tell you if they're here. What I can say is that our city is very, very, very tranquil."

Tranquility, as we've learned most recently and vividly in Iraq and Afghanistan, does not necessarily mean that the police and the government are in charge of a place. It can just as well mean that a warlord or cleric or smuggler enjoys de facto sovereignty.

These cases where the government is not meaningfully sovereign present a conundrum for U.S. foreign policy. What will it mean and how will we proceed if Las Zetas -- not the Mexican government itself -- has the greatest control over whether bullets will fly across the Rio Grande and once again hit the rec center at the University of Texas, Brownsville?