In a time of turmoil - and when isn't there turmoil somewhere? - it's advisable to be tuned-into travel advisories and warnings. Most governments issue such advice, along with safe-travel tips, for their citizens. Travelers don't necesarily need to heed warnings and somewhat milder advisories to the letter, but they are worth taking seriously.
United States citizens should check out "Current Travel Warnings'' posted on the U.S. State Department's Web site: http://travel.state.gov/travel. Frequently updated with useful information, the site highlights places where threats to travelers as well as broad public safety issues need to be considered. As of this writing, 19 February, 2011, there are 31 nations on the list. Some are obvious choices, for obvious reasons: Mexico (drug war), Iran (violently repressive, militantly Islamic regime), North Korea (xenophobic and totalitarian communist regime), Iraq and Afghanistan (long, grinding wars).
Perhaps surprisingly, considering the civil unrest sweeping the Arab world following the successful regime-changing public protests in Tunisia and Egypt, only Egypt, Saudi Arabia, Lebanon, Yemen and Algeria join Iraq as Arab nations on the list. Saudi has been there since 23 December of last year, Algeria since last April. Yemen was listed last October, as was Lebanon. Travelers should watch to see if other restive Arab nations such as Jordan go seriously wobbly.
About Saudi Arabia, the State Department warns: "There is an on-going security threat due to the continued presence of terrorist groups, some affiliated with Al Qaida, who may target Western interests, housing compounds, hotels, shopping areas, and other facilities where Westerners congregate.''
About Egypt, the department notes: "Due to continuing uncertainties regarding the restructuring of Egyptian government institutions, the security situation remains unresolved. Until the redeployment of Egyptian civilian police is fully restored, police response to emergency situations or reports of crime may be delayed. The Embassy's ability to respond to emergencies to assist U.S. citizens is also significantly diminished. The Embassy's current (reduced) staff level reduces the ability to travel to areas outside of Cairo, where the level of security remains unclear.''
Such nationwide travel warnings - note that they are not bans - have been criticized by some in international governments and the image-conscious travel industry as blunt instruments. When I interviewed then-Philipines tourism minister Richard Gordon last decade, he noted unsafe conditions apply to only a handful of his island country's thousands of islands.
Bottom line: Travelers don't have to totally avoid countries on travel-warning lists, but reading the lists and taking down contact information for your country's embassies and consulates is definitely a good idea - as is checking the lists often for updates.