The U.S. government is urging Americans not to travel to Yemen and said those already there should consider leaving.
In a travel warning issued Sunday, the State Department said the threat level in Yemen is "extremely high" due to terrorist activities and civil unrest.
The department said it has authorized the voluntary departure of family members of U.S. Embassy staff and non-essential personnel. It said that in the event of a crisis, evacuation options would be extremely limited.
Yemen has faced weeks of demonstrations by anti-government protesters calling for President Ali Abdullah Saleh to leave office. Clashes between government forces and opposition activists have turned deadly.
Terrorist organizations, including the Yemen-based al-Qaida in the Arabian Peninsula, are also active in the country.
Some information for this report was provided by AP, AFP and Reuters.
