A number of countries have updated their travel advice to the United States in the wake of a crackdown on immigration by the Trump administration. Travelers have reported being detained at the US border, even though they had valid travel visas. Germany updated its travel advisory for the US this week after a number of its citizens were detained at customs and then deported.

0:00 What's behind the Trump administrations strikt entry requirements
3:04 David Bier, Director of immigration studies at the Cato Institute in Washington, DC