Rahmanullah Lakanwal, 29, an Afghan national who is the suspect in the shooting of two National Guard members in Washington, DC. Photo / US Attorney's Office / AFPRahmanullah Lakanwal, 29, an Afghan national who is the suspect in the shooting of two National Guard members in Washington, DC. Photo / US Attorney’s Office / AFP

President Donald Trump pledged to suspend migration from "third-world countries" following the incident. Photo / Getty ImagesPresident Donald Trump pledged to suspend migration from “third-world countries” following the incident. Photo / Getty Images