AP Photo

On Tuesday, protests rocked the American embassy compound in Cairo, while heavily armed militias overran the U.S. consulate in Benghazi, Libya, killing U.S. Ambassador Christopher Stevens and several others. The incidents initially seemed related, but they are in fact dramatically different developments.

In Egypt, a 2,000-strong crowd of protesters gathered in front of the U.S. Embassy to protest a film that depicts Islam in crude and offensive ways. The film is apparently being promoted by an Egyptian-American Coptic Christian now living in the United States and Terry Jones, the Florida pastor of "International Burn a Koran Day" infamy.

At the American embassy in Cairo, some protesters scaled the walls and in the courtyard were able to take down an American flag and...