Revenge is not a new current in Mexico's drug wars. Journalists who investigate too deeply are often killed, making Mexico one of the most dangerous places to report from. Prosecutors seeking justice often face the same fate.

But suspected members of the La Familia cartel in the state of Michoacán gave new meaning to the word over the weekend – even in hardened Mexico – after gunmen shot up police stations across the country, killing five officers and two soldiers by the time the revenge attacks were over on Saturday.

Mexican authorities say the series of assaults, among the most brazen since Mexican President Felipe Calderón launched an antidrug offensive in Mexico in December 2006, were a direct response to the arrest of one of their alleged leaders early Saturday.

Mexico's 'Tet offensive'?

It was characterized as a Mexican version of the "Tet offensive" by one columnist – a turning point in a nation's loss of faith that Mexico can come out from under the force of organized crime. And that questioning is perhaps no greater than in Michoacán, Mr. Calderón's home state, where his military effort began, and where a grenade was launched in a public plaza last year.

"This attack and [the grenade incident] are not just simply examples of gang violence. They have a much more profound impact on the public psyche," says Bruce Bagley, a Latin America drugs expert at the University of Miami. "They erode confidence in Calderón's strategy and the legitimacy of the state response."

Brutal retaliation

Authorities told the Associated Press that the attacks were a retaliatory response to the arrest of Arnoldo Rueda Medina, believed to be a head of the La Familia cartel, on Saturday morning in Morelia, the capital of Michoacán.

Throughout that day, gunmen attacked federal police stations in seven cities across the state, as well as in Guanajuato and Guerrero states. The following day a hotel in Michoacán, in the port city of Lazaro Cardenas, was shot into but no one was injured.

Two men have since been arrested in the attacks against government authorities, among the worst the nation has seen since Calderón sent 45,000 troops across the country to lessen the grip of organized crime that reaches into police forces, government institutions, and mountain villas across the country. Some 11,000 people have been killed in drug-related violence since 2006.

But even here, where beheadings and public death threats are a new norm, the weekend attacks seemed to raise the stakes.

Writing in the Milenio newspaper, columnist Ciro Gómez Leyva described the public mood: "In the war against the narcos, July 11 seems like a kind of Tet offensive, the synchronized, made-for-Hollywood offensive by the ... North Vietnamese Army that, despite being characterized as a military disaster, created the perception that the otherwise invincible US army would never win in Vietnam."

Another blow to Calderón

The attacks over the weekend will do little to bolster Calderón's national action party, which already fared poorly well in legislative elections last week.

"The [drug gangs] are demonstrating to the government that their security strategy has only limited impact," says Mr. Bagley. "They demonstrated that they have ongoing capacity to intimidate, coerce, and carry out violence against police despite the militarization."

This message resounds in Michoacán, where the military has manned the streets the longest, and where La Familia has grown into one of the nation's most powerful outfits. "In Michoacán, they have become a force to be reckoned with," says Bagley.