Why does Mexico refuse to pay for the construction of the US-Mexico border wall?

On August 27th, the Mexican Foreign Ministry issued an announcement on the 27th, reiterating that Mexico will not pay for the construction of the US-Mexico border wall. The announcement said that Mexico "will not pay for the construction of the border wall or physical barrier between the two countries in the United States in any form under any conditions" and pointed out that this decision "is not Mexico's negotiation strategy, but one of the principles of safeguarding sovereignty and national dignity". ?

US President Trump said on social media Twitter on the same day: "Mexico is one of the countries with the highest crime rate in the world. We (the United States) need this' wall', and Mexico will pay this (construction) cost by reimbursement or other means. " ?

On August 22, Trump went to Arizona, which was his first visit to the US-Mexico border since he took office. Since taking office, Trump has repeatedly proposed to build a border wall on the US-Mexico border and insisted that the Mexican government pay the relevant fees, but it was rejected and protested by the Mexican government.

The US-Mexico border refers to the border between the United States and Mexico, starting from San Diego and Tijuana in the west and reaching Brownsville and matamoros in the east.

A few days ago, the American media released a set of photos showing the real scene of the border between the two countries. Since Trump took office, his plan to build a wall has been controversial. In fact, on the border between the United States and Mexico, various separation walls have already existed.

The border between the two countries is 3 169 kilometers long, with the Rio Grande as the boundary in the east, the Sonoran Desert and the Chihuahua Desert in the middle, and the metropolitan areas of Santiago and Tijuana and even the Pacific coast in the west. The scenery is changeable, ranging from a bustling metropolis to an endless desert.