And it’s not just arms, it’s military training and procedures. The cartel mentioned most often in the article (the Zetas) literally WERE the army - they were special forces and commandos that decided to become the muscle for the Gulf Cartel because it paid more.
Then the Gulf Cartel learned the problems of relying on mercenaries when the Zetas turned on them as well, becoming one of the most dominant cartels in the world.
Anyway, to answer your question: the cartels have tanks, helicopters, ships, submarines, mortars, grenades and missiles.
Many of them are crude versions of course (https://en.m.wikipedia.org/wiki/Narco_tank) but it’s definitely not just small arms fire.
A bunch of highly trained ex-commandos with billions in budget and hundreds of thousands of “troops” (in aggregate) that doesn’t much care about hurting civilians can do a lot of damage.
> 'What about mercenaries?' said Boggis.
> 'The problem with mercenaries,' said the Patrician, 'is that they need to be paid to start fighting. And, unless you are very lucky, you end up paying them even more to stop -'
(from the book Jingo by Sir Terry Pratchett).
It's so different to the reality that most of us inhabit that it's hard to imagine.
They literally overpowered and brought the city to a standstill.
They run Mexico, no illusions anymore. Still a beautiful place to visit fwiw.
Only the Zetas are really “offshoots”, having been started by former anti-drug special forces IIRC, the rest are more business partners.
> In May 2010 an NPR report collected allegations from dozens of sources, including U.S. and Mexican media, Mexican police officials, politicians, academics, and others, that Sinaloa Cartel had infiltrated and corrupted the Mexican federal government and the Mexican military by bribery and other means. According to a report by the U.S. Army Intelligence section in Leavenworth, over a 6-year period, of the 250,000 soldiers in the Mexican Army, 150,000 deserted and went into the drug industry.