Protecting US Citizens Abroad

Luke Somers is an American citizen photojournalist. He was working as a translator at a National Dialogue Conference, which was held at Sana'a, Yemen, as part of the United Nations Security Council Resolution 2051. It should be noted that Luke Somers was not an employee of the US government.
During Luke's presence in Sana'a, he was captured by Al Qaeda and was being held for ransom/negotiations, with threat of death. The Obama Administration ran a special task force to try to save Somers, but it failed. Al Qaeda has now executed Somers.
The question seems to be what do you do to protect American citizens in dangerous parts of the world? It's not an easy one to answer, but I think I can offer clarity on the subject.
The first thing to consider is whether a particular country is dangerous to American citizens. We can easily pick out a few that are not dangerous, such as Canada, Great Britain, France, Germany, and Italy. Some of the clearly dangerous ones are Iran, North Korea, and Libya. Some appear to be marginal, such as Mexico, Cuba, Lebanon, and Israel. However, I don't think that's specific enough.
I believe the United States government should designate which countries of the world are unsafe for Americans to travel and work in. Travel would mean entry to the country for business reasons, family contacts, tourism, missionary and other religious work. Perhaps the best test whether a country is dangerous for Americans is whether the United States maintains a working embassy with minimal security in the country.
If a country is on the dangerous list, the position of the United States should be that Americans are not restricted from entering or operating within the country, but the United States government will take no extraordinary means to protect them or save them from further harm if captured or detained. Persons excluded from that position would be all employees of the United States government, including military personnel, federal representatives and congressmen, State Department officials, spies, or any activity as long as they are on the federal government payroll. Note that this does not include state or local officials, such as governors or mayors. Retired government officials on pension would not be protected, except for US ex-presidents. I'm not sure what to do about the employees of contractors to the US government, but there should be a clear resolution.
Recovering a detained American government employee might occasionally involve payment of ransom or similar monetary negotiation. However, the standard US government action would usually be a declaration of war on the country or group involved in the capture or detention, followed by subsequent strong military action unless there is immediate release. The military action would only be terminated on the unimpeded release of the captured or detained US employee. Assassination of the US employee by the captors would be justification for continuation of the strong military action as a retribution and lesson to others who may be tempted to follow a similar route.