What makes Trump's statement particularly interesting, though not new, is that the notion of chain migration - which is the process by which an immigrant already in the country can sponsor a family member to join them - is that this is how his mother came to reside in the United States.
In defense of his statement on chain migration, Trump indicated that the New York attacker, Sayfullo Saipov, had helped 23 others come to the country since 2010, though this has not been confirmed.
"There's no way that in seven years someone would be able to bring 23 people to the United States. Chain migration doesn't work that fast," Executive director of Center for Immigration Studies, which advocates for reduced immigration, told Buzzfeed.
Trump also took aim at the Diversity Immigrant Visa program, which he termed a "Democrat Lottery System". The program grants about 50,000 visas each year, but it is not quite the "free ticket" Trump's term connotes.
"Think of it like a deli counter. The diversity lottery is just about getting the ticket," [New York Immigration attorney Neena Dutta] explained. "You still have to go up to the counter, get your item, pay and leave. And the diversity lottery is way more complicated than that, it's not as simple as picking out cheese."
Many experts and lawmakers have spoken out against Trump's rhetoric:
"I'm very concerned that in the face of all this nationalist rhetoric, with the marching of neo-Nazis in Charlottesville, that relations could regress to the point where the devaluation of the diversity becomes prominent again in this nation," said Rep. Yvette Clarke, who vowed to fight for the Diversity Visa program.