A border fence will cost Mexico much less than 8 Billion dollars to build.
What Trump is saying to Mexico is - build the fence and we will make sure you receive 8 billion in gifts in kind . You build it for less and you can keep the rest.
Mexico will build the fence in record time.
It's no skin off Mexico's nose, they have already exported as many of their poor, illiterate to the US as they can. They have not many more people available to send North.
Many illegals are from South and Central America these days and Mexico is building a wall on THEIR Southern border to stop them from entering and trashing Mexico.
Heck, Mexico could build a fence on their Southern and Northern borders for * billion and still have plenty left over for enough mordida to feather the nests of every one of Mexico's pols who matter
Trump isn’t going to let Mexico build The Wall, nor should he, they are not to be trusted for that part of this important project.
Mexico’s part is to pay for it.
Without a fence, migrants are sending $23 billion back to Mexico each year. Do the math.