President Donald Trump launched his sweeping immigration crackdown on Monday which included an order reinterpreting birthright citizenship, a principle that has been recognized in the United States for more than 150 years.

Mr. Trump is planning to attempt to deny birthright citizenship to the children of immigrants who are in the U.S. illegally, according to the incoming officials. The U.S. government has long interpreted the U.S. Constitution to mean that those born on American soil are citizens at birth, regardless of their parents' immigration status.

Attorneys general in 18 states sued Tuesday to block the order, saying birthright citizenship cannot be undone with the stroke of the president’s pen.