That's an awfully big stretch of speculation that reaches a comforting conclusion.
From the AP story (FBI: No evidence Mexico hit men targeted Americans):
Confused hit men may have gone to the wrong party, the FBI said Tuesday as it cast doubt on fears that the slaying of three people with ties to the U.S. consulate shows that Mexican drug cartels have launched an offensive against U.S. government employees.
Gunmen chased two white SUVs from the birthday party of a consulate employee's child on Saturday and opened fire as horrified relatives screamed. The two near-simultaneous attacks left three adults dead and at least two children wounded.
The working theory, described to the AP by FBI spokeswoman Andrea Simmons, drives home just how dangerous Ciudad Juarez has become — and just how vulnerable those who live and work there can be, despite the Mexican government's claims that most victims are drug smugglers.
According to the line of investigation, the assailants — believed to be aligned with the Juarez drug cartel — may have been ordered to attack a white SUV leaving a party and mistakenly went to the "Barquito de Papel," which puts on children's parties and whose name means "Paper Boat."
"We don't have any information that these folks were directly targeted because of their employment by the U.S. government or their U.S. citizenship," Simmons said by phone from El Paso, just across the Rio Grande from Ciudad Juarez.
Well, Special Agent Simmons also 'doesn't have any information' that the killers were just confused, does she?
The article goes on to quote a private analyst who doubts the cartels would have the huevos to attack U.S. government employees, because that would provoke a heightened response from both the U.S. and Mexican governments.
But why wouldn't the narcos be willing to strike directly at U.S. interest targets, especially soft ones? Aren't the narcos facing an "existential threat" from the U.S.-supported Mexican federal government's narcotics control campaign, as is stated on page 14 of the State Department's 2010 International Narcotics Control Strategy Report that was released to Congress two weeks ago?
"We believe that the Mexican government's efforts are having a real impact. For the first time, trafficking organizations are facing an existential threat from the state, which they cannot win by bribery or intimidation."
The Mexican drug cartels are fighting for their survival at this point. Given enough provocation, such as news stories about the escalating levels of U.S. support for Mexico's campaign against them (see, for example, this WaPo report from February 24: U.S. to embed agents in Mexican law enforcement units battling cartels in Juarez), I think they certainly would strike at U.S. employees. What would they have to lose?