Statistics released by the Mexican government showed that criminal groups' attacks on army and federal police helicopters have increased since the launch of the government's drug war five years ago, with 28 reported since 2008.
No helicopters come under fire in the first two years of the drug war, according to the figures, with the first reports coming in 2008 when four choppers were attacked in separate incidents. This number increased to six in 2009 and 14 in 2010, before dropping to three in 2011.
The Associated Press notes that the 2011 figures are likely an underestimate. The Federal Police refuse to release data on attacks against their helicopters, though they admitted to one incident in May of that year.
In the reported attacks, helicopters were generally damaged by bullets from automatic rifles, causing generally minor damage to rotors, windshields and fuselages. The most severe attack came on a federal police's chopper in May 2011 when the bullets hit two officers and the craft was forced to land.
The attacks have not caused any fatalities on the government's side, and only a small number of injuries.
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The fact that most aircraft suffered only minor damage suggests that the drug gangs have so far been unable to obtain military grade weaponry, despite reports in May 2011 that Mexico's cartels -- in that particular case the Sinaloa Cartel -- were trying to obtain weapons including surface-to-air missiles.
Attempts by drug gangs to strike against their aerial foes, which also now include unmanned aerial vehicles (UAVs), or drones, provided by the US, have not been highly successful, and do not indicate a qualitative change in the conflict.