BUILDING THE WALL - And Mexico IS going to pay for it. Enter the International Emergency Economic Powers Act (IEEPA): https://en.wikipedia.org/wiki/International_Emergency_Economic_Powers_Act "The International Emergency Economic Powers Act (IEEPA), Title II of Pub.L. 95–223, 91 Stat. 1626, enacted October 28, 1977, is a United States federal law authorizing the President to regulate commerce after declaring a national emergency in response to any unusual and extraordinary threat to the United States which has a foreign source.[1]" Details: https://www.law.cornell.edu/uscode/text/50/1701 Interestingly, even CNN doesn't push back on the Executive powers: "But Stephen Vladeck, a law professor at the University of Texas and a CNN legal analyst, said what Trump is doing under the law may very well be within the authority Congress gives the White House -- though it's just as surely not what Congress ever intended." Source: https://www.cnn.com/2019/05/31/politics/mexico-tariffs-emergency-powers-act/index.html What we are watching is 5D chess.  POTUS knew all along that the legal challenges to funding and building the wall would impede its progress, both public and privately-funded.  The military is building, but more movement is needed.  POTUS kept the IEEPA in his hip pocket and is now playing that card. If Mexico complies - they will have to build a wall in certain areas, just to meet enforcement compliance.  If they do not comply, the tariffs will further fund the wall construction.  It is unclear what/how the the tariffs may be used.   Mexico is going to pay for the wall one way or another, even if the wall = immigration enforcement vs construction of the wall.