Mexicans, aghast at the rising body count, the mutilated corpses on their streets and the swagger of the drug chieftains, wonder if they are paying too high a price in pursuing organized crime groups that have operated for generations on their soil. “Sometimes, I think this is a war you can’t really win,” a Mexican soldier whispered to a reporter, out of earshot of his commander, during a recent drug patrol in Reynosa. “You do what you can, but there’s so many more of them than us.”

Image Mexican Army soldiers on a night patrol in Reynosa. Drug cartels in Mexico bring in billions of dollars more than the government spends to defeat them. Credit... Adriana Zehbrauskas for The New York Times

Americans, including border state governors and military analysts in Washington, have begun to question whether the spillover violence presents a threat to their own national security, and, to the outrage of many Mexicans, whether the country itself will crumble under the strain of the war.

A War’s Origins

The impetus for the drug war began during President Felipe Calderón’s 2006 campaign.

Although the economy was the No. 1 issue, Mr. Calderón, a law-and-order technocrat, was paying attention to a steady rise in criminality early on. Mr. Calderón received threats on his life from drug cartels during the campaign, fueling his outrage, according to officials close to him. And he began to suspect that drug money was finding its way into political parties.

After a nail-biter of a victory, by about half of a percent of the 41 million ballots cast, so close that his main opponent still does not recognize it, Mr. Calderón opted to send the army into the streets to fight the drug cartels. He aimed for the bold step to win the support of the crime-weary population and to bolster his legitimacy as the president for all Mexicans.

While his contested election seemed to fade quickly from public discussion, the drug war proved a bigger headache. About 28 months down the line, the government trumpets record seizures of drugs, money and guns to show that it is striking serious blows against the traffickers.

As further evidence of success, the government cites the tens of thousands of arrests it has made of rank-and-file members of the four main Mexican cartels and of some of the kingpins leading them. Recently, three top traffickers have been arrested, including one accused of organizing an assault on the United States Consulate in Monterrey.

The United States Drug Enforcement Administration says Mexico’s battle against drugs is clamping down on supplies, citing the doubling of cocaine prices in the United States over the past two years.