In the aftermath of the terror attack at a mosque in Sinai in which more than 300 were murdered, Egyptian President Abdel Fattah el-Sisi vowed to avenge the victims and bring “brute force” to bear against the perpetrators. The attack in Egypt is already one of the world’s most deadly this year and Cairo has responded strongly. The question is whether it will mark a turning point in the conflict in Sinai and throughout Egypt.The attack in Sinai brings to the surface a largely unreported war against terrorism that has gone on in the peninsula for years, in which hundreds have been killed. With Islamic State largely defeated in Syria and Iraq, attention will now turn to the struggle Egypt is facing. Israel is also watching Cairo’s strategy closely, fearing spillover and expressing solidarity with Egypt.In a televised address six hours after gunmen attacked a mosque in El-Arish, Sisi said his country was facing a wave of terror on behalf of the world. “What is happening is aimed at stopping our efforts to confront terrorism. It is aimed at destroying our will,” he said. He vowed the massive attack would result in increased determination and unity among Egyptians to root out terrorism.With Islamic State’s widespread losses in Syria and Iraq, the attack might reflect an attempt by the group’s affiliate in Sinai, Wilayat Sinai, to put itself on the world map. After an al-Shabaab attack in Somalia that killed 358 people in October, and the May attack in Kabul, Afghanistan, that killed 150, Friday’s Sinai attack stands out for its deadly scale. It has similarities with other massive attacks, such as those on Karrada Street in Baghdad last year; the Garissa University attack in Kenya and Paris attacks in 2015; Kenya in 2013; and Mumbai in 2009.Terrorist attacks are not only becoming bloodier, but mosques have increasingly become a target of ISIS-style attacks.Mosques in Yemen, Nigeria, Pakistan, Syria and Iraq have frequently been targeted and hundreds have been killed. When the final victim count is in, Friday’s bombing is likely to be the deadliest terrorist attack in Egyptian history, after the 2015 bombing of Metrojet Flight 9268 over Sinai. The attack also comes just after the 20-year anniversary of the Luxor massacre.Targeting a mosque in Sinai represents a new strategy for terrorists in the peninsula.Previously, various jihadist groups had targeted tourists from 2004 to 2006, and focused their attacks on security forces.In 2012, however, the Sheikh Zuweid Sufi shrine was blown up in Sinai.This was part of a pattern of attacks on Sufis that also saw a car bombing targeting the Ahmad al-Badawi Sufi mosque in Tanta outside Sinai.In February, ISIS began targeting Christians in Sinai, as they had at St. Mark’s Cathedral in Cairo in December 2016. In that month, seven Christians were killed and numerous families fled El-Arish for safer areas, such as Ismailia. In March, ISIS executed two men for “sorcery” and in April, it targeted St. Catherine’s Monastery at Mount Sinai. In April and May, ISIS attacked Christians outside of Sinai, in Alexandria and in Minya, killing 56.The patterns illustrate that the insurgency in Sinai and its tactics are linked to those outside the peninsula.A review of ISIS attacks in Sinai this year reveals that before the November 24 attack, most victims of terrorism had been security forces – either Egyptian police or soldiers. Although official casualty figures are not available, the victims of major attacks this year include at least 92 soldiers and police victims, as well as hundreds injured.In many cases, the Egyptian government has responded to major attacks by retaliatory raids, including air strikes.For instance, when 23 Egyptian soldiers were killed in North Sinai in July, the military released video showing an air strike they said killed 40 terrorists. A day later, Egyptian police said they had killed another 14 of the enemy in battles.The full story of the largely unseen battles in Sinai may never be known. Twitter accounts, devoted to monitoring terrorism, post statements by ISIS that claim frequent attacks. Between March and May, those claims were made almost every few days.At the same time, Twitter accounts, which seek to follow military operations, show the extent of the battle against terrorism, involving columns of MRAPs, tanks, drones, special operations and snipers.ISIS employs not only car bombs and shooting attacks, but sophisticated attacks on checkpoints involving mobile car bombings (VBIEDs), trucks with heavy machine guns mounted on the back, RPGs and gradstyle rockets.The number of attacks appear to have turned North Sinai into a low-level war zone with numerous checkpoints and a major army presence.It also comes as Egypt mentors the Palestinian reconciliation talks that followed an agreement signed in October.Egypt has opposed Hamas rule in Gaza, and some of the terrorism in Sinai is connected to Gaza because the weapons that have been smuggled into Sinai were, in the past, destined for the Strip.However, Egypt has shut down the smuggling infrastructure in Rafah, flooding and destroying hundreds of tunnels and creating a buffer zone around the city.Egyptian media have stressed the solidarity shown by the international community in the wake of Friday’s attack, including condemnations from the US, UK, France, Saudi Arabia and Russia. There are reports the military is already responding by attacking terrorist hideouts in central Sinai. In addition, more details of the attack have come in, including that the terrorists arrived in two cars and targeted Sufi worshipers, among others.The question facing Egypt is what kind of strategy can it pursue after years of being unable to tamp down terrorism in Sinai.It has tried using the “brute” force that Sisi promises will be used again. It has avenged victims before. Yet, its well-equipped army has been unable to reduce the violence.Through the attack on the mosque, the perpetrators want to show they can strike anywhere, including against civilians at Friday prayers.One of the issues Egypt faces is that it has largely fought its war against terrorism in Sinai in the shadows. Reports emerge from time to time of the scale of the fighting and what is taking place.Many things remain unclear, however, such as the degree of support for ISIS among central and northern Sinai Beduin and other groups in Sinai.In the wake of major attacks in El-Arish, 2015 was supposed to see a new strategy. In January 2015, for instance, Sisi created a Unified Command for the Area East of the Canal, putting the war against terrorism in Sinai under the command of Osama Askar, formerly the head of Egypt’s Third Army.Sisi may want to shake up his security establishment again, but he just made major changes in October, removing and appointing new security officials.Cairo wants international support for the conflict in Sinai, but it doesn’t want the international scrutiny that would come along with it. This creates a difficult situation. Egypt has the manpower and weaponry to fight a terrorist insurgency.If official reports are accurate, casualties among ISIS and other groups have been high. However, like in Afghanistan, northern Nigeria, Yemen or Somalia, casualties are not a good indicator of whether insurgencies are growing or being defeated.So far, Egypt has not found a solution, and regional models in Africa and the Middle East show there may not be a clear path forward.