Mexican officials are trying to calm concerns over reported US infringement of its southern neighbour's sovereignty.
According to a New York Times report, US intelligence agents are operating in Mexico more than ever before to infiltrate drug cartels in Mexico,
The newspaper cited security officials who said US unmanned surveillance planes and sophisticated human-intelligence gathering systems have helped Mexican authorities to kill or capture dozens of other prominent suspects involved in the drug war.
Al Jazeera's Franc Contreras reports from Mexico City.
