Pretty interesting topic. The last war with Mexico,1846 termed intervención estadounidense en México, was over land. Because of it we pretty much gained the southwest and most of the west coast...granted that was during the 19th Century and people were of a different mindset then, but the point is that it wouldn't be the first time we as a nation have invaded south...are the problems caused by the cartels a national security risk? You bet. But you aren't going to have an official here in the "beltway" ever say we need to invade another sovereign nation...ten years of war have done nothing to change the mindset of politicians...there isn't anything lucrative enough to be gained (either fiscally or politically) to warrant military interdiction. As for the legalization of controlled substances...well as mentioned earlier by others, prohibition didn't stop alcohol use but it did provide a very lucrative few years for the bootleggers...but in the end when the Volstead Act was repealed, criminals moved on to other things...just me, stay safe