Three horrendous killings Saturday in Ciudad Juarez, Mexico, just over the border from El Paso, Texas, underlined the severity of the influence of drug cartels in Mexico, but also sounded a warning to Americans.

Shot dead were an employee of the U.S. consulate general, her husband and the husband of another U.S. employee. What was new was not the execution-style killings, but that these were the first American government officials to have fallen victim to them.

The spreading poison of the cartels in Mexico, which cause some observers to fear that the country of 112 million is becoming a drug culture, is alarming to Americans. One reason is the historic close U.S. relationship with Mexico. A second is there are many Mexicans in the United States, in both legal and illegal status. A third is that, although maintaining law and order in Mexico is clearly the business of the Mexican government, and not the United States, the fact is that Mexico's drug cartels depend for their existence on the hungry market for their product on this side of the border.

The basic relationship between the United States and Mexico will remain in spite of the drug trade and its corresponding slaughter, which has now spread from Mexicans to Americans. While there is grumbling in the United States about the impact on jobs here of the 1994 North America Free Trade Agreement, particularly in light of the recession, last year nearly half of Mexico's imports, $140 billion worth, came from the United States. Mexico was the second-largest destination for American exports, second only to Canada, the other partner in NAFTA.

In spite of U.S. efforts to control the nearly 2,000-mile border, it remains porous and the idea of building a fence and wall along it was abandoned recently as not the most effective method to address the problem.

U.S. aid to Mexico through the Drug Enforcement Agency, the FBI and the Immigration and Naturalization Service to improve coordination and to tighten border procedures and control the trade in arms across the border is worth pursuing. President Barack Obama is reportedly considering an increase in aid in the aftermath of last weekend's killings. President Felipe Calderon of Mexico is using the Mexican army to curb violence along its northern border. U.S.-Mexican military cooperation has too sensitive a history to offer much promise.

Probably the best action the U.S. government could take to help alleviate the drug cartel problem would be to modify America's own drug policy. The problem is twofold in nature: supply of product from Mexico and demand for it from the United States. It is a matter that cries out to be addressed from both ends.

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