美国国务院：将叙利亚的旅行警告提升至四级，并敦促美国人不要前往叙利亚。叙利亚任何部分都不应被视为免于暴力的安全地区。

Core Viewpoint - The U.S. State Department has raised the travel warning for Syria to Level 4, advising Americans not to travel to Syria, indicating that no part of Syria should be considered safe from violence [1] Summary by Relevant Categories - Travel Advisory - The travel warning for Syria has been elevated to Level 4, which is the highest level of warning [1] - The advisory strongly urges U.S. citizens to avoid all travel to Syria due to safety concerns [1] - Safety Concerns - The State Department emphasizes that there are no areas in Syria that can be deemed free from violence [1]