四级旅行警告: 建议美国公民避免所有国际旅行

四级旅行警告：由于COIVD19的全球冲击，美国国务院建议美国公民避免所有国际旅行。在仍有商业离境选项的国家，常驻美国的美国公民应安排立即返回。

在国外旅行的美国公民如不希望返回，应做好准备在国外无限期停留。居住在国外的美国公民应避免所有国际旅行。

https://china.usembassy-china.org.cn/zh/travel-advisory-level-4-03202020-zh/

Travel Advisory: Level 4 - The Department of State advises U.S. citizens to avoid all international travel due to the global impact of #COVID19. In countries where commercial departure options remain available, U.S. citizens who live in the US should arrange for immediate return.

U.S. citizens traveling abroad that do not wish to return should be prepared to remain abroad for an indefinite period.  U.S. citizens who live abroad should avoid all international travel.  https://travel.state.gov/content/travel/en/traveladvisories/ea/travel-advisory-alert-global-level-4-health-advisory-issue.html