Within days of taking office, President Trump ordered sweeping changes to immigration enforcement both at the border and within the United States, kicking off dramatic changes in how unauthorized immigrants, would-be refugees, and international travelers are handled. In this discussion, a high-ranking former Bush administration Department of Homeland Security official, former Mexican Ambassador to the United States, and Brookings Institution scholar examine the administration’s initiatives, ranging from the contested travel ban and reductions in refugee resettlement to changes in enforcement policy and practice, repointing the legal immigration system into one focused on “merit-based” admissions, building a border wall, and more. This fast-paced panel, moderated by MPI’s Doris Meissner, discusses the policies and ideas, challenges in their implementation, and responses from states, Congress, the judicial branch, and other actors.