The U.S. Department of State has issued updated travel advisories to help keep American citizens safe while abroad. These warnings use a four-level tier system to guide travelers based on the security risks in each country — ranging from routine caution to an outright “do not travel” alert. Advisory levels The travel advisory system includes four categories, starting with “exercise normal precautions.” This is the lowest risk level, but still warns of conditions that may differ from the U.S.