Standing with Israel

Imagine that the cartels took control of Mexico and every year for the last twenty years fired at least a thousand rockets into the United States raining fear and death down on San Diego, Yuma, Tucson, El Paso, and other cities. Then the Mexican cartels conducted a barrage of over 3,000 rockets on American targets. They followed this with an armed invasion. Before the U.S. military could push them out, the cartels killed a total of 1,139 Americans including more than 695 civilians, including thirty-six children, and kidnapped more than 240 hostages. All of that is hypothetical but I ask the reader, what would the United States do if it suffered such an attack across its southern border?