The U.S. Department of State has placed a Travel Warning on travel by U.S. citizens to Israel, Saudi Arabia, Lebanon, and several other Middle Eastern and/or Arabic-speaking countries. This means citizens are urged to “consider very carefully whether you should go to [that] country at all.” Here’s the link with the full list of countries with Travel Warnings/Alerts and explanations for each. I’d stay away from any countries on that list.
http://travel.state.gov/content/passports/english/alertswarnings.html