AL ARISH, EGYPT // To a Sinai bedouin, footprints in the sand can speak volumes.
A day after the 10th bombing of a pipeline that provides natural gas to Israel and Jordan near the village of Midan in this frontier region of Egypt, Abdel Moneim Harb decided to investigate the dunes himself for clues.
What he found were five sets of footprints: the steady steps of a Sinai man, and four clumsy foreigners following close behind.
"Nothing can be done in our lands without a guide," said Mr Harb, 36, who travels widely across North Sinai as a tribal property dealer. "But the footprints show outsiders were involved."
The footprints he saw on December 18 are just a small piece of the puzzle of the bombings, a deadly assault on a police station in Al Arish and attacks on Israel from Egyptian soil that have emerged in the security vacuum after the uprising that forced Hosni Mubarak from power.
The evidence points to an alliance of long-dormant extremist groups and foreign supporters, possibly based in the Gaza Strip.
Rooting out violent extremists in this far-flung corner of Egypt has become one of the most important security concerns for the military, which is balancing its role in running the government during the transition after Mubarak's resignation with its traditional responsibility for national security.
The resurgence on the peninsula of groups such as Takfir wal-Hijra, an Islamist extremist organisation dating to the 1960s, has put new pressure on Egypt's relations with Israel and posed questions about the military's ability to prevent clashes along its borders. It is also a task for the new government, still being formed, to improve the livelihoods of a Sinai population long repressed by the Mubarak regime.
Sinai, 60,000 square kilometres of mountains, deserts and coasts on the Red Sea and the Mediterranean, has a population of about half a million. It is at once one of Egypt's least populous lands, and its most tumultuous.
The Egyptian military, with the agreement of the Israelis, swept into Sinai in August in what it dubbed Operation Eagle to clamp down on the violence. About 20,000 soldiers set up checkpoints and moved in on suspects and weapons smugglers. Despite their efforts, the pipeline attacks have continued.
Under the 1978 Camp David Accords, Sinai was returned to Egypt, but conditions included the Egyptian government agreeing not to station military forces there.
Retired Maj Gen Sameh Seif Al Yazal, a consultant to the Supreme Council of the Armed Forces (Scaf), said the army was now exploring the possibility of installing an array of sensors and cameras along the pipeline to discourage more attacks along the roughly 250km section from the city of Taba to Al Arish.
"They can't have men everywhere all the time," he said. "The idea now is to use technology to solve the security problem."
Israel has fast-tracked the construction of a steel wall on its side of the border, after a deadly incident on August 18 near the resort of Eilat. Eight Israelis were killed and more than 30 were injured in attacks on a bus full of tourists by assailants who crossed into Israel from Sinai.
Several of the men arrested by the military so far have admitted to being members of Takfir wal-Hijra, a group that has been relatively inactive in Egypt for the past three decades, said Reg Maj Gen Al Yazal. He said the men admitted they were part of a particular offshoot, the Shukri Mustafa Wing, which takes its name from an agricultural engineer who was executed in 1978 for his role in kidnapping and killing a government minister.
"The fact that they call themselves the Shukri Mustafa Wing means they believe they have to correct the state of society with aggression," he said. "That's what they were trying to do until the second army of Egypt entered the area. The situation has improved somewhat, but there have still been attacks."
Mustafa was the founder of Jama'at Al Muslimin, a radical group that took inspiration from Sayyid Qutb's idea that even Egyptian Muslims were worthy targets of attacks because they failed to fight against an un-Islamic government.
The name Takfir wal-Hijra, which means excommunication and exile, came from Egyptian newspapers and marked the group's decline as an increasingly marginal movement. In 1977, Muhammad Al Dhahabi, a critic of the group and a minister of Awqaf, or Islamic endowments, was kidnapped and killed. Hundreds of group members were soon arrested and Mustafa was executed after being found guilty by a military tribunal in 1978.
Sinai Bedouins say modern-day Takfir wal-Hijra members live in isolation have not had a wide following in recent years.
Ali Abu Ghoneim, 40, a farmer in Toma, a tiny village nestled in desert hills, said members rarely engaged with residents of north Sinai and refused to send their children to public schools. But when police fled their posts on January 28 after the collapse of the Ministry of Interior amid demonstrations in the rest of Egypt, many of them began to exhibit a more confident swagger.
"Suddenly, they started coming out more and terrorising the area," he said, although the army's push into Sinai late last year had quietened things down somewhat. "These people have a completely different mentality. They are brainwashed. They don't even realise they are being supported by other powers."
If not for Sinai's strategic location, Takfir wal-Hijra would not be a major threat. But being based so close to Israel and with ready access to smuggled weapons from tunnels connected to Gaza, the group's re-emergence is of particular concern to Egypt and its neighbours.
For Mr Harb, the property dealer who found the footprints near the bombing site, the answer to security in Sinai is not just in militarising the peninsula. Long neglected by Mubarak's government, the residents of Sinai are seeking more development, recognition of tribal ownership rights and making residents partners in security.
"If we had more jobs, more education, more health care, there would be less resentment," he said. "Smuggling is bread for some people. Just like the sand prints - the military needs us as the guide and we want their support."