The US State Department has launched a new travel advisory program.

The new system, which replaces the department's travel warnings and advisories, assigns a travel advisory level from 1 to 4 to every country in the world:

• Level 1 - Exercise Normal Precautions: Lowest-level advisory level for safety and security risk;
• Level 2 - Exercise Increased Caution: Be aware of heightened risks to safety and security;
• Level 3 - Reconsider Travel: At this level, the State Department advises travelers to avoid travel because of serious risks to safety and security; 
• Level 4 - Do Not Travel: This is the highest advisory level, warning of "greater likelihood of life-threatening risks." At this level, the U.S. government may have "very limited ability to provide assistance" to travelers. Travelers are urged not to travel to these countries or to depart as soon as it is safe to leave. The Department of State advises that U.S. citizens not travel to the country or leave as soon as it is safe to do so.  

Under the new system, level 1 and 2 countries will be reviewed every year, and level 3 and 4 countries will be reviewed every six months or in the case of a situation that prompts a review, the State Department says.

https://www.state.gov/r/pa/prs/ps/2018/01/276945.htm