Many protesters also heckled a small crowd that chanted "the military and the people are one hand" — a slogan first used by protesters when army troops replaced the hated police on the streets during the 18-day anti-Mubarak uprising.
Abdullah el-Sinawi, a prominent commentator close to the military, said Saturday's statement was a warning to Morsi and his Islamist backers to reach an agreement with their opponents to prevent the country's security from unraveling.
"We don't want a coup, and the military itself doesn't want to return to politics. But if it is forced to interfere to restore security, it will," el-Sinawi said. "The onus is on Morsi."
Mostafa el-Naggar, a former lawmaker and protest leader during last year's anti-Mubarak uprising, speculated that it could not have been easy for the military to issue the statement after the scathing criticism it endured for its running of the country starting from Mubarak's ouster in February, 2011 and June this year when it handed power to Morsi, the country's first civilian and freely elected president.
"It means a return to political life," el-Naggar said of the statement. "The military is saying it is still here and will interfere when necessary."
Egypt's military long enjoyed an aura of invincibility. All four presidents before Morsi hailed from the army, which considers itself the ultimate guarantor of the nation's sovereignty and safety.
Army generals taking powerful jobs on retirement in the state-owned public sector and as provincial governors ensured that the military's influence extended beyond the armed forces, which have over the years built an economic empire above oversight of any kind. But its reputation was shattered in the aftermath of Mubarak's ouster.
Until Morsi came to power in June as the nation's first freely elected president, Egypt's military had been struggling with protesters accusing it of trying to stall the transition to democracy after Mubarak was ousted by a popular uprising in February 2011.
It faced allegations of human rights violations, including torturing detainees, and scenes of elite troops beating up peaceful protesters, including women, on the streets hurt its standing as the defender of the nation.
This week's scenes of Brotherhood supporters armed with sticks carrying out military-type drills on streets close to Morsi's palace in the upscale Heliopolis district have revived suspicions that the fundamentalist group is running militias and made the prospect of an army intervention more palatable.
"The escalation of the conflict into civil strife becomes a risk to the military's interests and the country as a whole," said Michael W. Hanna, an Egypt expert from the New York-based Century Foundation. "So, the statement is a reminder of the potential role of the military and a signal for civilians to manage the political process."
Egypt's ongoing crisis is the worst since Mubarak's ouster, with the two sides repeatedly bringing out tens of thousands of supporters on the streets and the two sides at times fighting each other with firebombs, sticks and rocks. Offices of Morsi's Muslim Brotherhood have been attacked, sometimes torched, by his opponents. With neither side willing to compromise and a flurry of threats of violence by radical Islamists, the specter of more and widespread violence is real.
Omar Abdel-Halim, a 28-year-old veteran of the 2011 uprising, says he and his comrades will reserve judgment on a possible intervention by the military to end the violence.
If there is large scale bloodshed between the revolutionaries and the Islamists, he added, the army may not even be able to end it. "I think troops will just deploy to protect state institutions. They are not equipped to go after combatants on side streets and in alleys."
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