President Abdel-Fattah el-Sissi, a former general who led the 2013 military ouster of an elected Islamist president, also dismissed suggestions of military mismanagement, saying he and the defense minister personally approve all spending.
"There is a ferocious campaign against the state and the armed forces," el-Sissi said in his first public comments on the subject.
"This is your army, the army of your country. Your sons. It is not anyone else's army."
The military's economic activities date back to the 1970s, and since then the armed forces have built factories, hotels, bridges and roads. The military also runs gas stations, farms and livestock enterprises.
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The military has significantly broadened its economic profile in the three years since the overthrow of President Mohammed Morsi, the country's first freely elected leader.
Today it supervises massive infrastructure projects and runs a retail network that distributes food at discounted prices.
Earlier this month, the military said it would directly import baby formula to counter shortages. The move was ridiculed by many on social media and re-energized a longstanding debate over whether the military is devoting too much attention to its economic ventures at the expense of national security.
El-Sissi said the military could deploy across the entire country in six hours if needed.
"No one, thanks be to God, can harm the Egyptian state," he said, raising his voice. "Let no one think that we will abandon it (Egypt) or allow it to be taken away from us ... I am responsible before God, you and history to defend it until the very last moment.