President Donald Trump has banned travel to the U.S. by citizens of 12 countries and restricted access for those from seven others, citing national security concerns in resurrecting and expanding a hallmark policy from his first term that will mostly affect people from Africa and the Middle East.

A Trump administration travel ban that severely restricts the entry of nationals from Haiti, Cuba, and Venezuela into the United States starts Monday, and it’s yet unclear about how the policy will affect operations at Miami International Airport.

People from a dozen countries will soon be barred from entering the U.S., while those from seven others face expanded travel conditions, after President Donald Trump signed a travel ban on Wednesday.