A string of attacks killed nine members of Egypt's security and military forces and hit the country's main satellite communications station, in an apparent retaliation by Islamic militants a day after more than 50 supporters of the ousted president were killed in clashes with police.
The attacks show a dangerous expansion of targets, including the first strike against civilian infrastructure in the heart of the capital. They also blur the lines between the wave of Islamist protests against the military ouster of President Mohammed Morsi, and an insurgency that had been previously been largely confined to the northern Sinai Peninsula.
It is also likely to harden positions of the military-backed government and its opponents, making reconciliation more difficult.
"We are at war with them," said Mohammed Ibrahim, the country's interior minister in charge of security forces, pointing to militant groups. He suggested the surge in attacks, particularly the targeting of the satellite station- which left a minor damage on one of the dishes - was in retaliation for the government crackdown on Sunday's protests.
"This is an attempt to prove they are still around and are not broken," he told The Associated Press, without specifying which groups are behind the attacks. "They also aim to confuse, to distract" security forces.
In another development Monday likely to give momentum to the government crackdown on Islamists, a panel of judges recommended the dissolution of the Muslim Brotherhood's political party, the Freedom and Justice Party, which was registered months after the 2011 ouster of autocrat Hosni Mubarak.
The judges' recommendation said the party represents an outlawed group. The recommendations will be delivered to a Cairo court reviewing a case demanding the party's dissolution on October 19.
Another court had already ordered a ban on the Brotherhood's activities, and froze its assets, a decision currently reviewed by a government appointed committee amid legal challenges from group members.
Ashraf Badreddin, a member of the FJP, said authorities had already shut down offices of the party long before a court decision, telling Doha-based satellite broadcaster Al-Jazeera Mubasher Masr that the recommendation was "politicised".
At least 2,000 of the group's leading and mid-level members have been detained, including Morsi, and head of the FJP, Saad el-Katatni. Most of them will face trial on charges that range from murder and inciting violence to abuse of power and conspiring with foreign powers. Hundreds others died in a violent crackdown on protests and sit-ins held by Morsi supporters.
Authorities accuse pro-Morsi supporters of seeking to create chaos to discredit the new government. The government declared it is waging a war against terrorism.
Pro-Morsi supporters deny they resort to violence.
Ahmed Mostafa, a Brotherhood student leader, said there are plans to hold rallies at universities this week to denounce the killings and the military leaders, saying authorities are engaged in a campaign to pull his group and supporters toward violence, or armed confrontation. There are also calls for protest in Cairo's central Tahrir Square.
He dismissed accusations that Islamists are behind the surge in attacks.
"We reaffirm that peacefulness of our actions is stronger than weapons," he said. Such attacks, he said, "may be fabrications by intelligence agencies to justify their campaign against (us)."
A suicide bomber struck a security headquarters in the town of el-Tor, in southern Sinai, earlier Monday, killing three policemen, wounding 55 others, and damaging the building.
Southern Sinai is famous for its beach resorts such as Sharm el-Sheikh and has been generally spared the violence of the northern tip of the peninsula in the past six years. Attacks there in 2005 and 2006 left dozens, including tourists, dead.
Near-daily attacks against security forces and soldiers in the volatile northern Sinai Peninsula have increasingly resembled a full-fledged insurgency, especially in the three months since the ouster of Morsi. Ibrahim said counter-insurgency operations there have pushed militants into neighbouring southern Sinai.
The body parts of the suicide bomber in el-Tor are still being analysed to determine who was behind the attack, Ibrahim said.
In another attack, masked gunmen pulled alongside a pickup truck full of troops on patrol near the Suez Canal and opened fire, killing six soldiers, security officials said on condition of anonymity because they were not authorised to brief reporters.
And in a brazen targeting of a civilian infrastructure, gunmen believed to be hiding in nearby buildings fired a projectile into the compound housing the satellite dishes just before dawn, leaving a hole in one but causing no disruption of communications. Earlier, security officials said they believed rocket-propelled grenades were used in the attack, but Ibrahim said it was unlikely.
The surge in violence in the aftermath of the coup has raised questions about whether extremist sympathizers of Morsi, and others within his Brotherhood group, are using such attacks to bargain with authorities for a political goal, said political science professor Gamal Abdel-Gawad.
On the other hand, he said: "The government in Egypt is more prepared to deal with terrorism rather than with political instability.
"This is a security apparatus that has long experience in dealing with terrorism," he said in reference to a wave of terror attacks in the late 1980s and 1990s that targeted Egypt's security forces, liberal figures, politicians, Christians, and tourist resorts.
The violence is certain to set back efforts by the interim, military-backed government to revive the economy, especially the vital tourism sector, and bring order to the streets of Cairo, where crime and lawlessness have been rife.
In a sign of increased nervousness, security measures were heightened at Cairo International Airport Monday, with authorities using explosives detectors and dogs to inspect vehicles.
Abdel-Gawad said the targeting of the communications centre appeared aimed at "paralysing" symbols of the modern state by disrupting communications, but added that it was too early to say whether this is a new trend.
Abdel-Gawad said militants now have more capabilities than before. This time around also, "there are more people willing to grant legitimacy to terrorist activities because of the political developments," he said.