@Fokker
"Indeed, but the problem was made considerably worse when the deportations to, for example, El Salvador put powerful members of MS-13 in a country which didn't stand a chance of preventing them taking control of large sections of the country. That may have been because of the countries lack of infrastructure and organisztion, but ultimately I'm wondering if someone, somewhere down the line, made a bad call.
Possibly still are making a bad call."
To say that non-federal authorities made a "bad call" is kinda moot when you realize that when it comes to illegal immigrants, it would be best to just deport them in general. You have to remember that MS13 back then wasn't a powerful gang and its members had (somewhat) noble intentions. The US has been doing this to all other illegal immigrants that would also create gangs and cause trouble, so to say that deporting was a "bad call" is only a result of hindsight.
"The USA has the ability to use preventative measures regarding gangs, as has been proven in the past, which are far more successful than plain old punishments and threats, and yet it seems that regarding MS-13 the preferred method of dealing with the problem is deportation, which merely moves the members to a country that cannot control them, let alone punish them effectively due to MS-13 virtually running the prisons, turning them into makeshift headquarters."
I don't think anyone can fully understand how MS13 grew so rapidly and aggressively, and it would indeed be most likely due to a weak Salvadoran counter-measure, but I don't think it is because of a lack of US responsibility. You can't quite deport immigrants to a different country other than their origin (if we could, we'd send them all to Canada or something
). I think it's quite a tragedy that MS13 has grown so far from its original purpose upon creation, but because of the way they act, they have drawn international attention and that will be their undoing.