Mexico is not only unwilling, but really doesn't need one. Afterall, they have their military forces positioned on the Guatalaman border and have for quite some time. Who needs a wall when you have American supplied munitions, armaments and firearms? True they buy from other countries, but the US generally has the best bulk prices. This was exhibited when several Mexican military Hummers commanded by Mexican military soldiers armed with Mexican military American produced equipment and weapons crossed 50 miles into Texas last year. Mexico stated it was not their army, but drug smugglers and coyotes who had either purchased or stolen from Mexican military munition depots.