Police in Mexico's most violent city are finding themselves increasingly under target.

After a renewed crackdown on violence began having an effect in Ciudad Juarez, located on the border with the US, drug cartels have struck back, promising to kill a police officer each day.

Colin Harding, a specialist in Latin American politics, told Al Jazeera the police in Ciudad Juarez "are under tremendous pressure".

"Far from limiting and restricting the violence, if anything, the highly militarised policy that President Calderon has been following has spread it and the body count is going up all the time," he said.

Al Jazeera's Rachel Levin reports from Ciudad Juarez on the steps police are now taking to protect themselves.