A war of words has erupted between the United States and Mexico over President Donald Trump’s executive order to build a wall along the border, and his insistence that Mexico foot the bill. When the proposal was first announced during the U.S. election, it prompted an expletive-laden response from former Mexican President Vicente Fox. After the order was signed, Mexican President Enrique Peña Nieto canceled a planned visit to Washington.

My research explores how security interests shape immigration and border policies. In Mexico, migration is viewed as mutually beneficial and a fundamental human right. In the United States, migration is often viewed as a threat. The tension between these two impulses has produced what some Mexican government officials have regarded as a “bittersweet” relationship with the United States.

Do Trump’s policies signal a sea change in U.S.-Mexico relations and in the way the border is managed? Or just another shift in the ebb and flow of border management between the two countries?