In a sweeping move echoing his first term, U.S. President Donald Trump has enacted a fresh travel ban on 12 nations, citing national security threats. Critics say the ban disproportionately targets African and Muslim-majority countries, reigniting controversy over Trump’s hardline immigration agenda.

U.S. President Donald Trump's order banning citizens of 12 countries from entering the United States goes into effect at 12:01 am ET (0401 GMT) on Monday, a move the president promulgated to protect the country from "foreign terrorists.

Here is a closer look at why the administration says it is instituting full bans on foreign nationals traveling to the U.S. from 12 nations.