For a few weeks this spring, it appeared that Mexico’s bloody drug war might be subsiding. Levels of violence in some of the worst locales, especially Ciudad Juarez and Tijuana, had declined from the peak in 2009 and 2010, and stories about beheadings and mass graves were no longer daily fare in wire-service reports. But with the onset of summer, hopes about a sustained improvement are fading fast.

The news over the past few days has been especially grim, as the headlines make all too clear. “At least 41 killed as Mexico scrambles in drug war,” (AFP, July 9), “11 bodies found on outskirts of Mexico City” (AP, July 9), “At least 17 killed in northern Mexico bar massacre,” (AP, July 9), “Ten decapitated bodies left in truck in Mexico,” (Reuters, July 10).

Three aspects of the stories are particularly ominous. First, until recently, Mexico City and its suburbs were largely immune from the gruesome battles among rival cartels. The incident of 11 bodies being dumped in Chalco, just outside the national capital, though, is the latest confirmation that Mexico City’s immunity is largely a thing of the past. The reality is that violent incidents there have been on the rise since late 2010. This new atrocity should shatter what remains of the complacency among the city’s political and economic elite.

Second, the “scramble” referred to in the AP story is the decision to send another 1,800 federal agents into Michoacan, President Felipe Calderon’s home state. That move was deemed necessary because of the increased boldness of the Knights Templar, a successor group to La Familia, which had been the leading drug cartel in that state. Just last year, the Calderon government boasted that it had basically put La Familia out of business after killing the group’s principal leader. As on so many other occasions in Mexico’s drug war, that proclamation of victory was decidedly premature.

Third, the biggest contributor to the death toll of 41 was the massacre of some 20 (up from the original count of 17) people following a cartel assault on a bar in Monterrey, Mexico’s leading industrial city and a crucial component of the country’s economy. That episode continues a deteriorating trend in what was once an exceptionally peaceful city, not just in Mexico, but in all of Latin America.

Despite the brief pause this spring, the carnage of Mexico’s drug battles goes on. Indeed, even with the modest decline in the pace earlier this year, the body count since Calderon declared war on the cartels in December 2006 has now soared beyond 40,000.

The festering security sore on our southern frontier has not healed, and it’s not likely to do so in the foreseeable future. Instead of pursuing the fool’s errand of nation building in Afghanistan or trying to keep a permanent U.S. military presence in Iraq (despite previous promises to the contrary), the president and his national security team need to pay attention to a serious problem much closer to home. And U.S. officials need to accept the reality that America’s prohibitionist strategy regarding drugs plays into the hands of the violent criminal elements that run Mexico’s cartels. Those individuals derive their profits (and their power) from the lucrative black market that prohibition creates. We need a change in policy before we wake up one day and there is a full-blown narcostate on the Rio Grande.