Cairo — President Abdel Fattah el-Sisi on Monday made dramatic efforts to reassure Egypt’s Coptic Christians — a pillar of his government’s support — as they buried victims of a bombing on Sunday at their cathedral in Cairo, an act that has stirred fears of resurgent Islamist violence.
Standing alongside Pope Tawadros II, the leader of the Coptic Church, Mr. Sisi identified a 22-year-old man who he said detonated a suicide vest in a chapel on the grounds of St. Mark’s Coptic Orthodox Cathedral, the seat of Egypt’s Orthodox Christian Church, during Mass. At least 25 people, most of them women, died in the attack, the deadliest in years against Egyptian Christians.
Mr. Sisi said the authorities had arrested four of the bomber’s accomplices and were looking for two others.
The speed of the official response reflected a broader sense of alarm in Egypt after three bombings in three days that shattered a monthslong period of calm outside the Sinai Peninsula, where a violent insurgency has long flared. An explosion at a security checkpoint in Cairo on Friday killed six police officers, and a smaller blast in the northern town of Kafr el-Sheikh later that day, aimed at the police, killed a passing motorcyclist.
As well as battling insurgents, Mr. Sisi has been scrambling to shore up his support. His popularity has been battered this year by a gnawing economic crisis that has caused widespread discontent, with soaring inflation and shortages of staple food products like sugar. Threatened street protests, however, have not materialized.
Under Pope Tawadros, the Coptic Church has been among Mr. Sisi’s staunchest supporters, calculating that Mr. Sisi, a general who formerly led Egypt’s armed forces, can protect Christians from Islamist militants. A bomb attack on a church in Alexandria during a New Year’s service in 2011 killed 23 people and wounded almost 100.
The compact has come under strain this year as Mr. Sisi has struggled to contain attacks on Copts in Upper Egypt and, now, a major terrorist bombing in the symbolic heart of the Egyptian Orthodox Church.
After the bombing on Sunday, angry protesters gathered at the cathedral gates, shouting insults at Mr. Sisi’s government, calling for the resignation of the interior minister and pushing away several pro-Sisi television journalists.
That fury appeared to have abated somewhat on Monday as Mr. Sisi sought to assure Coptic leaders that the authorities, in identifying the man suspected of being the bomber, had solved the case. Turning to face Pope Tawadros, he said, “We could not come here to you, your holiness the pope, without knowing the basics of the case.”
Egyptian officials reported further arrests late Monday, but did not give further details.
Many Egyptians, however, including some Copts, were skeptical that the authorities could have unveiled the plot so quickly. “It seems dubious in many ways,” said Wael Eskander, a prominent blogger. And militancy experts said the nakedly sectarian attack offered alarming proof that Egypt’s hydra-headed Islamist insurgency is growing in complexity and ambition.
Although no group claimed responsibility for the cathedral attack, Mr. Sisi appeared to pin the blame on the Muslim Brotherhood, whose leader, Mohamed Morsi, was ousted as president by the military in 2013, and which has since been outlawed.
Without identifying the Brotherhood by name, Mr. Sisi said the bombing was the work of forces that “have spent three years trying to shake us” — a reference to the same period in which his government has instituted a fierce crackdown on Brotherhood supporters, thousands of whom have been jailed.
But experts say the bombing was more likely carried out by a Salafist group like the Islamic State or Al Qaeda, which have a long history of sectarian massacres. Hasm, a group officials have linked to disaffected Muslim Brotherhood supporters, and which claimed the earlier bombing in Cairo on Friday, has mostly directed its attacks at state or security officials.
“This is the most complex insurgency Egypt has seen in its modern history,” said Mokhtar Awad, a research fellow at the Program on Extremism at George Washington University. “We have competing militant groups, all with the goal of destabilizing the government and causing havoc.”
Early details about the trajectory of Mahmoud Shafik Mohamed Mostafa, the man blamed for the bombing on Sunday, illustrates the challenge.
Mr. Mostafa first came to public attention in 2014, when he was arrested at a Muslim Brotherhood protest in Fayoum, south of Cairo. Local news media reports showed a photograph of Mr. Mostafa, his face bloodied and his arms bound, standing with another suspect alongside a rifle and ammunition the police said they had seized from them. Yasmin Hosam El Din, a lawyer who represented Mr. Mostafa at the time, said in a Facebook post on Monday that he had been tortured in custody and was released in 2015.
But of late Mr. Mostafa has become known by the alias Abu Dagana el-Kanani — a sign, experts say, of possible recruitment by a Salafist group like the Islamic State.
“There have been numerous cases of Egyptian Islamists who went to Libya and the Levant, by way of Sudan, and dived into the fight with Islamic State,” Mr. Awad said. While he lacked independent information about Mr. Mostafa, Mr. Awad said that such a path was “consistent with how the group has been operating in Egypt.”
One wing of the Islamic State in Egypt is battling the Egyptian Army in the Sinai Peninsula while another operates through underground cells in major cities. But rights groups say that Mr. Sisi also bears some responsibility for the insurgency. The imprisonment of tens of thousands of opposition supporters, many of whom have been tortured, has helped radicalize young Egyptians, they say.