The “caravan” is a test of the USA’s resolve to repel one from the vulnerable southern border. After all, Kerry declaring the Monroe Doctrine “over” was an open invitation to foreign powers into Central and South America.
The invasion has lots of historical precedent. Given the hordes attempting to invade California, the Inchon like landing to the enemies rear is justified as a national security matter.
Rather than defensively treat symptoms, the better course is to cut out and kill the cancer