MEXICO CITY - Instead of bringing relief, the recent capture of drug lords in northern Mexico has raised fears of new turf wars in border cities that are major US trafficking routes.
The violence between the Zetas and Gulf cartels has been so great in the state of Tamaulipas, which borders Texas, that newspapers no longer report on drug-related crime and residents are afraid of openly talking about gangs.
Last month, the government detained Zetas leader Miguel Angel Trevino, alias "Z-40," capturing a man whose cartel is accused of some of the most gruesome crimes in Mexico, including massacres of scores of migrants and beheading of rivals.
Then last weekend, troops nabbed Gulf Cartel boss Mario Ramirez Trevino, dealing a blow to a criminal organisation already severely weakened by major arrests, internal divisions and its violent split with the Zetas, its former paramilitary wing, in 2010.
But residents of Nuevo Laredo, a city considered a Zetas fiefdom, and Reynosa, home to the Gulf cartel, are holding their breath for potential internal wars of succession or incursions by rivals such as the Sinaloa cartel.
The government says it has ramped up security in Tamaulipas to prevent any new violence following the captures. The state's murder rate rose from 10 per 100,000 inhabitants in 2009 to 46 per 100,000 last year.
"Now we're waiting to see what happens," said Carlos Alberto Renteria, a shop owner in Nuevo Laredo, a city of 370,000 people through which one-third of Mexican land exports travel - along with drugs stashed in vehicles.
Pablo, a teenager who admits working as a lookout for the Zetas, said the gang "says that things will continue as before, that nothing has changed and that Z-42 is now in control."
Security experts believe that Trevino's brother Omar, known as Z-42, has taken over the Zetas and that the cartel appears to still be holding together despite its top leader's arrest.
Nuevo Laredo has witnessed horrific scenes in recent years. In May last year, 14 bodies were dumped in front of City Hall and nine others were hung from a bridge.
The Gulf Cartel run by Ramirez, alias "X-20," controls the drug trade in Reynosa, a city of 600,000 people, but his arrest may prompt the Zetas to launch a raid.
"People are very afraid. They don't know what will happen, but nobody wants to talk about it," said a journalist based in Reynosa, who like most people in the region asked to remain anonymous.
Analysts say it is unclear whether Mexico's most wanted drug kingpin, Sinaloa cartel boss Joaquin "El Chapo" Guzman, will make a new bid for Nuevo Laredo despite his defeat there in 2005.
"Nuevo Laredo is the crown jewel, so if people perceived the Zetas as being weak, they would have pushed to take it. But we haven't seen that at all," Scott Stewart, analyst at the US intelligence consultancy Stratfor, told AFP.
While it is considered the most powerful cartel in Mexico, the Sinaloa crime syndicate "is not immune or untouchable," Stewart said, adding that the takedowns of drug lords may lead to a "Balkanization" of drug cartels.
The arrests are the biggest anti-cartel coups for President Enrique Pena Nieto, who took office in December vowing to tweak the security strategy of his predecessor, Felipe Calderon, whose six-year tenure was marked by 70,000 drug-related murders.
While the government says the operations are examples of the strategy's use of intelligence and better coordination between agencies, analysts say Pena Nieto has largely continued Calderon's focus on arresting capos and deploying the military.
Alejandro Hope, a former Mexican intelligence official, said the government will have to readjust its strategy to focus on more local policing because big cartels will soon be history.
Hope foresees the emergence of multiple smaller gangs working at the local level and dedicating themselves to various crimes including extortion, kidnapping and drug trafficking.
"What we will have is an ecosystem of crime that is much more complex," Hope told AFP.
"The nature of the threat is changing but the threat remains."