Egypt’s ruling military junta, the Supreme Council of the Armed Forces, launched a deadly attack on thousands of protesters encamped in Tahrir Square on Saturday morning. Security forces killed six protesters, while the Egyptian health ministry reported that 71 people had been hospitalized.

The attack followed a huge demonstration that took place in Tahrir Square on Friday night. The crowd was estimated at several hundred thousand, reportedly the largest protest since the fall of Hosni Mubarak on February 11.

The huge crowd in Tahrir Square, the epicenter of the mass protests that helped bring down Mubarak, demanded that the military regime rapidly hand over power to an elected civilian authority.

Many chanted that the military junta was identical to the old Mubarak regime. “Tantawi is Mubarak and Mubarak is Tantawi,” the crowd called out, in reference to the top Egyptian armed forces officer, Field Marshal Hussein Tantawi.

Tantawi has led the country since the ouster of Mubarak. He is widely despised in Egypt, having been one of Mubarak’s key henchmen for decades. Protesters also called for the prosecution of Mubarak, his sons Gamal and Alaa, and other officials accused of torture and corruption.

At around 3am local time on Saturday, soldiers and police attacked the Tahrir Square sit-in using tear gas grenades, baton charges, taser guns and live ammunition. Facing down the security forces, large numbers of protesters held their ground, forcing the army to withdraw.

Following the attack, the military issued a statement blaming “outlaws” for rioting, while denying that anyone had been killed or injured by the army or police.

Having failed to crush the demonstration, the army threatened to clear the square on Saturday night. “Tahrir Square will be emptied of protesters with firmness and force to ensure life goes back to normal,” Major General Adel Emarah, a member of the Supreme Council, told a news conference on Saturday.

However, protesters defied the military regime’s 2am to 5am curfew by maintaining a constant overnight presence in Tahrir Square. Those camping out took defensive measures to protect themselves from the armed forces and police, barricading the square with barbed wire.

“We will continue the sit-in until our demands are met,” protester Ahmed el-Moqdami, 25, told Reuters on Saturday. “First of all, the field marshal must go. Mubarak must be put on trial and a civilian council must be formed for the transition period.”

On Sunday, over a thousand people rallied in Tahrir Square to continue voicing their demands. Demonstrators cried “Revolution, revolution,” and burned an effigy of Tantawi. Placards read, “What we want is a civilian council,” and “The people demand the field marshal be toppled.”

Reuters reported that twelve armored personnel carriers full of troops waited near the square, but the armed forces and police kept out of sight.

The Egyptian military were able to achieve some popular backing in the run-up to Mubarak’s ouster and in the period immediately afterwards, largely thanks to the uncritical support given to the generals by bourgeois opposition figures such as Mohammed El-Baradei and the Muslim Brotherhood party. But the anti-democratic character of the military junta has been exposed to the masses more clearly in recent weeks.

Faced with ongoing strikes for improved wages and job security, and protests calling for social and democratic reforms, the military rulers have turned to increasingly repressive measures. On March 23, the military banned all strikes and protests and imposed severe punishments for those taking part in any public expression of opposition to the regime.

Reacting to the ongoing mass opposition to the regime, the Muslim Brotherhood announced on Thursday that it backed street protests calling for the prosecution of Mubarak and some government officials. The Brotherhood has refused to take part in protests for weeks, and is still working behind the scenes with Egypt’s military rulers.

Abdullah Helmy, a leader of the Revolutionary Youth Union, one of the groups formed around the anti-Mubarak protests, told the Wall Street Journal that the Muslim Brotherhood was “afraid of losing momentum” and were rejoining the demonstrations only in order to bolster their chances in parliamentary elections proposed for September this year.

The crackdown on Friday night allowed the junta to test the water for future repression. For now, the regime has backed off from a major confrontation with the working class, and has reportedly offered the minor concession of dismissing some unpopular regional governors who had been appointed by Mubarak.

But the military is opposed to any genuine expression of the demands of the Egyptian working class and rural poor. The military high command was an integral part of Mubarak’s regime, and many senior officers have become very wealthy from the privatization of swathes of Egypt’s economy.

Any trial of Mubarak would be a political embarrassment to the current regime, the Egyptian capitalist class in general, and the Western governments and companies that had long and lucrative relations with Mubarak.

On Sunday, Mubarak made his first televised statement since leaving office, opposing any investigation into his crimes and those of his family. Speaking from his luxury compound in the Red Sea resort of Sharm el-Sheikh, Mubarak told the Al-Arabiya satellite network that the rumors of his looting the economy were “unjust campaigns and untrue allegations.”

“They aim to tarnish my reputation and discredit my integrity,” the ex-president stated. He added that he reserved his “legal rights towards whoever tried to ruin my and my family’s reputation.”

Mubarak, his wife and their two sons continue to live in great comfort under the protection of the military. However, fearing a mass popular backlash, Egypt’s chief prosecutor has banned them from leaving the country, and their assets have been frozen. Some reports suggest that the Mubarak family’s fortune may be between $40 billion and $70 billion.

The Egyptian junta has the complete backing of the United States government, continuing the close relationship that Washington cultivated with the Egyptian military under Mubarak.

US imperialism has relied on the Egyptian military for decades as a vital ally in policing the region. Not only did the armed forces provide the backbone of the Mubarak government, helping to oversee the reorganization of the Egyptian economy in the interests of the transnational corporations, but it has also played a key role in assisting Washington’s closest ally, Israel, in the oppression of the Palestinians in Gaza.

Backing Mubarak until the very last, the Obama administration only abandoned the dictator when it became clear that the Egyptian uprising threatened the entire Egyptian bourgeoisie and the interests of imperialism. Washington then shifted gears to ensure that the fall of its long-time ally did not disrupt these US interests.

Washington threw its weight behind the military government as a bulwark against the mass protests and strikes, and recent visits to Cairo by US Secretary of State Hillary Clinton and Defense Secretary Robert Gates have been aimed at getting back to business as usual.

Of crucial importance to Washington is the assurance given by the generals that Egypt will abide by its agreements to cooperate with the Israel Defense Forces and the Pentagon. Showing its subordination to the predatory interests of the imperialist powers in North Africa, the Egyptian military has been acting as a cat’s paw for the US in the Libyan conflict, supplying weapons to the CIA-backed “rebel” leadership in Benghazi.

Looking to continue the IMF-backed structural adjustment policies that have turned Egypt into a cheap labor haven for big business, the Obama administration has also been working with its allies in Cairo to develop a US-Egypt Enterprise Fund. The aim of this new body is to “stimulate private sector investment, support competitive markets, and provide business with access to low-cost capital,” according to the US State Department web site.