The U.S. has Visa Waiver Program (VWP) that allows citizens of several countries to travel to the U.S. without a visa.
Entry isn't guaranteed and exceptions do apply. There is Visa Waiver Program Improvement and Terrorist Travel Prevention Act of 2015 (VWPITTPA), which enforces (among everything else) the following,
travelers in the following categories are no longer eligible to travel or be admitted to the United States, without a waiver, under the VWP:
Nationals of VWP countries who have traveled to or been present in Iraq, North Korea, Syria, Iran, Sudan, Libya, Somalia, or Yemen at any time on or after March 1, 2011 (with limited exceptions)...
I noticed that VWPITTPA Act was passed in 2015, whereas it applies to travelers from 2011 onwards. In other words, VWPITTPA applies retroactively. This seems to imply that a law-abiding individual from VWP-eligible countries, from 2011 to 2015, must have known that they shouldn't or mustn't to travel to Iraq, North Korea, Syria, Iran, Sudan, Libya, Somalia, or Yemen.
- What is the implied criteria for VWP-eligible individual to know not to travel to these countries from 2011 to 2015? For example, is it implied that an individual is watches the news, consults American embassies or consulates abroad about their travel plans, or perhaps something else?
- Let's say a VWP-eligible individual plans to travel to questionable, but otherwise unrestricted locations, such as Venezuela. Based upon the criteria above, can it be reasonably predicted that such individial will be barred from entering the U.S. via VWP in the future?
P.S. I am not a national of any of these countries, nor did I ever travel to these countries listed in VWPITTPA. I'm just curious about the reasoning here.