CAIRO — On Sunday, a bomb ripped through a tourist bus in the resort town of Taba, killing at least three foreign tourists and the Egyptian bus driver. Taba is located in Egypt's restive Sinai Peninsula on the border with Israel, a region as well known for its beautiful beaches and amazing coral as it is for its smuggling routes, rebellious residents, and homegrown terrorist groups.

Since Sinai is both the base of the growing insurgency against Egypt's military government and one of Egypt's top tourist destinations, it might seem obvious that such an attack would take place here. But the fact that militants blatantly targeted civilians and tourists should be deeply troubling, and shows that this cancerous conflict is metastasizing.

Since the military takeover, violence has become routine across Egypt. Communities rich and poor have been torn apart by brutal clashes between protesters calling for the restoration of civilian government and police defending the military regime. More than 1,000 people have been killed in the violence, mostly at the hands of security forces. Thousands more have been arrested for taking part in protests or criticizing the military.

Last month, I woke up to a huge car bomb detonating in front of the Security Directorate building in my neighborhood. The blasts that rocked Cairo that day killed six people, and were claimed by a shadowy jihadi group known as Ansar Beit Al Maqdis (ABAN), the same group responsible for the Taba bombing.

ABAN has long opposed Egypt's secular institutions. And while supporters of the military regime believe there are direct connections between the Muslim Brotherhood and ABAN, the two groups publicly disagree about goals and tactics. The Muslim Brotherhood has embraced and dominated the democratic process while ABAN believes constitutional democracy is inherently un-Islamic. Instead, it advocates violent jihad and immediate implementation of sharia law.

Despite the brutal nature of ABAN, the group has largely avoided attacking civilians and tourists. Besides some disgusting but small-scale attacks on Egyptian Christians, ABAN almost exclusively has targeted the security forces.

So why the apparent abandonment of this policy? ABAN and groups like it have two major bases, the Sinai Bedouin community and veterans of the Egyptian jihadi movement of the 1990s. Bedouins are culturally and linguistically different from other Egyptians and have been subjected to decades of land appropriations, collective punishment, and systematic underdevelopment at the hands of the central government. Some Bedouins support jihadis as a a way of trying to strike back at the police and military. However, powerful Bedouin sheiks also profit from the tourist industry in Sinai, and seem to have been protecting tourists and the money they bring.

In the 1990s, old-school jihadis learned the hard way that mass attacks on tourists alienate the bulk of Egyptians. The naked brutality and economic stupidity of their attacks turned the Egyptian public against the jihadis and justified Mubarak's successful crackdown against them.

But now, Egyptian security forces have been cracking down hard on the Bedouins of north Sinai. Details are sketchy, but there are reports of a scorched earth policy, of the government killing people indiscriminately and butchering the herds of livestock that Bedouins rely on to survive.

Meanwhile, many urban youths are becoming disillusioned with peaceful activism. An acquaintance of mine, a participant in both the democracy movement of 2011 and the Muslim Brotherhood dominated anti-coup movement, saw several of his friends brutally killed by police. He was almost killed himself on August 14, 2013, when security forces killed several hundred people in a single day. He told me he was making arrangements to go to Sinai to "pick up a Kalashnikov," but was eventually talked out of this by a Muslim Brotherhood activist. Many similarly disaffected youths are surely not talked out of it.

The fall of the Muslim Brotherhood and the brutality of the security forces have provided the jihadi groups with a huge crop of enraged, reckless young men eager to avenge their martyred friends. At the same time, the Bedouin sheiks, who once moderated jihadi behavior, are now desperate enough to green-light almost any action that will hurt the Egyptian government.

If this bombing is the beginning of a new phase of the Egyptian conflict, it will be a disaster. While the tourist industry is a shell of its former self, it still provides Egypt with the hard currency it needs. The Egyptian economy simply can't take any more hits. As the situation worsens, more young people will flock to terrorist groups and thuggish "popular committees" that the government organizes to beat up journalists and attack protesters. Average Egyptians, who simply want things to get better, have no recourse as the largest Arab nation slides further into poverty, instability, and senseless violence.