Egyptian Defense Minister Abdel-Fattah el-Sissi warned his country could be on the brink of collapse if the current protests continue.
About 60 people have been killed in five days of political violence that began on the second anniversary of Egypt's revolution.
Political opponents of President Mohammed Morsi are angry over the growing influence of Islamists in his government and his attempts to grab more power.
Morsi declared a state of emergency in three cities along the Suez Canal, ordering in the military and establishing a curfew. But those actions only led to more fighting and deaths.
"The deployment of the armed forces poses a grave predicament for us insofar as how we balance avoiding confrontations with Egyptian citizens, their right to protest and the protection and security of vital facilities that impact Egypt's national security," el-Sissi said.
Nearly 500 people have been injured in the protests by secular Egyptians who resent Morsi's authoritarian style of government and predisposition toward an Islamist state under Sharia law.