CIUDAD JUAREZ, Mexico - Drug cartels are sending a brutal message to police and soldiers in cities across Mexico: Join us or die.
The threat appears in recruiting banners hung across roadsides and in publicly posted death lists. Cops get warnings over their two-way radios. At least four high-ranking police officials were gunned down this month, including Mexico's acting federal police chief.
Mexico has battled for years to clean up its security forces and win them the public's respect. But Mexicans generally assume police and even soldiers are corrupt until proven otherwise, and the honest ones lack resources, training and the assurance that their colleagues are watching their backs. Here, the taboo on cop-killing familiar to Americans seems hardly to apply.
Police who take on the cartels feel isolated and vulnerable when they become targets, as did 22 commanders in Ciudad Juarez when drug traffickers named them on a handwritten death list left at a monument to fallen police this year. It was addressed to "those who still don't believe" in the power of the cartels.
Of the 22, seven have been killed and three wounded in assassination attempts. Of the others, all but one have quit, and city officials said he didn't want to be interviewed.
On Sunday, city spokesman Sergio Belmonte confirmed that Juarez's police chief had submitted his resignation and said he would be replaced by a military official on leave from the armed forces.
"These are attacks directed at the top commanders of the city police, and it is not just happening in Ciudad Juarez," Mayor Jose Reyes Ferriz said at the funeral of the latest victim, police director Juan Antonio Roman Garcia. "It is happening in Nuevo Laredo, in Tijuana, in this entire region," he said. "They are attacking top commanders to destabilize the police force."
The killings are in response to a crackdown launched by President Felipe Calderon, who has sent thousands of soldiers and federal police across the nation to confront the cartels. Drug lords have hit back by sending killers to attack police with hand grenades and assault rifles.
Police are increasingly giving up. Last week, U.S. officials revealed that three Mexican police commanders have crossed into the United States to request asylum, saying they are unprotected and fear for their lives.
"It's almost like a military fight," said Jayson Ahern, the deputy commissioner of U.S. Customs and Border Protection. "I don't think that generally the American public has any sense of the level of violence that occurs on the border."
On May 8, Edgar Millan Gomez, who had taken over as acting federal police chief, just 10 weeks previously, was shot by a lone gunman outside his Mexico City apartment. Police blamed the Sinaloa cartel and said a police officer was among the suspects arrested.
The U.S. Embassy in the capital flew its flag at half-staff. "Mexico has lost another hero," Ambassador Tony Garza said in a statement. "Mexico has lost too many heroes in the fight against criminals and drug cartels."
Mexican government institutions didn't lower their flags, but held elaborate funerals.
In Ciudad Juarez, police have been given assault rifles — they used to just carry pistols — but also are instructed not to patrol streets alone. More than 100 of the city's 1,700-member force have resigned or retired since January.
Soldiers are also in the cartels' sights. The Zetas, an infamous group of soldiers-turned-drug hit men, strung banners above highways with slogans such as "The Zetas want you — we offer good salaries to soldiers," and taunts about low army pay.
The conflict has become a battle for the loyalty of police and civilians.
"Juarez Needs You! Join up and become part of the city police," say enormous city billboards. The jobs offer salaries about three times higher than those offered by the foreign-owned "maquiladora" factories that are the city's biggest industrial employer.
But police and soldiers keep deserting to the cartels, giving traffickers inside knowledge about tactics and surveillance.
And because of their history of corruption and abuse, police and soldiers run into suspicion as they patrol the border slums where traffickers throw children's parties, hand out cell phones and employ taxi drivers and youths as lookouts.
A Mexican army captain leading about a dozen soldiers raiding a Ciudad Juarez slum gazed over a maze of alleys, shacks and, in the distance, El Paso, Texas, gleaming in the sun. He said the drug lords' spies are everywhere, tipping off their bosses to approaching troops.
Many residents complain of heavy-handed army tactics.
"These guys don't care about anything," Lalo Lucero, 44, a former migrant worker in New Mexico, said as he watched soldiers detain a neighborhood youth. "They came into my house without a warrant, searched through everything and told me to sit on a couch and not say anything."
The army's public relations office did not reply to requests for comment. But authorities have tried to improve the troops' image by blanketing Ciudad Juarez with pictures of a soldier manning a machine gun and the slogan "We Are Here to Help You."