From the U.S. State Department:
The Department of State urges U.S. citizens to avoid all travel to Lebanon because of current safety and security concerns. U.S. citizens living and working in Lebanon should understand that they accept risks in remaining and should carefully consider those risks. ...
Up-to-date information on travel and security can also be obtained by calling 1-888-407-4747 toll-free in the United States and Canada or, for callers outside the United States and Canada, on a regular toll line at 1-202-501-4444. These numbers are available from 8:00 a.m. to 8:00 p.m. Eastern Time, Monday through Friday (except U.S. federal holidays).
For further information, U.S. citizens should consult the Department of State’s Country Specific Information for Lebanon. You can also stay up to date by bookmarking our Bureau of Consular Affairs website, which also contains current Travel Warnings and Travel Alerts.
U.S. State Department Warning