The Islamic State claimed responsibility for the attacks in Brussels that left at least 30 dead.
Months earlier, coordinated attacks across Paris that left 130 dead were a clear indication of the "group’s adoption of global terror tactics to boost its profile and strike back at its enemies."
To really understand the Islamic State and how the group operates, we recommend you read these five stories:
Yes, there has been a huge influx of foreign fighters joining the Islamic State in Iraq and Syria. But the real decision makers aren't foreigners, but former members of Saddam Hussein's Baathist regime.
Even with the influx of thousands of foreign fighters, almost all of the leaders of the Islamic State are former Iraqi officers, including the members of its shadowy military and security committees, and the majority of its emirs and princes, according to Iraqis, Syrians and analysts who study the group.
2. Inside the surreal world of the Islamic State’s propaganda machine, by Greg Miller and Souad Mekhennet
An exclusive report about media operations inside cities operated by the Islamic State revealed startling new facts. Filmmakers inside the caliphate, for example, made seven times more than a typical fighter and were given houses and cars.
“The media people are more important than the soldiers,” he said. “Their monthly income is higher. They have better cars. They have the power to encourage those inside to fight and the power to bring more recruits to the Islamic State.”
Camera crews would fan out across the cities every day, resembling a "medieval reality show."
Camera crews fan out across the caliphate every day, their ubiquitous presence distorting the events they purportedly document. Battle scenes and public beheadings are so scripted and staged that fighters and executioners often perform multiple takes and read their lines from cue cards.
3. The U.S.-Islamic State propaganda wars, by Greg Miller and Scott Higham
Islamic extremist propaganda went from Osama bin Laden's long sermons from a cave to highly produced Islamic State recruiting videos. The U.S., on the other hand, tried to counter or thwart the extremist message but is still struggling. Even though the United States has killed Osama bin Laden and thwarted mass-casualty attacks after Sept.11, 2001, "Al-Qaeda’s brand of militant ideology, however, has only spread."
A clear result of the war with the Islamic State is an unrecognizable Middle East. An Islamic State supply route, for example, has "mostly erased Syria-Iraq border."
As fighting among dozens of different groups continues, "there is no single unifying plan, and no overarching goal, only a jigsaw puzzle composed of the collapsed fragments of Iraq and Syria."
5. Life under the Islamic State: Spoils for the rulers, terror for the ruled, by Kevin Sullivan
"The Islamic State has drawn tens of thousands of people from around the world by promising paradise in the Muslim homeland it has established on conquered territory in Syria and Iraq," writes Sullivan. But the reality is quite different:
The militants have created a brutal, two-tiered society, where daily life is starkly different for the occupiers and the occupied, according to interviews with more than three dozen people who are now living in, or have recently fled, the Islamic State.
6. How the Syrian revolt went so horribly, tragically wrong, by Liz Sly
About five years ago, there were peaceful protests in Syria in an attempt to bring democracy to the region. What was known as the Arab Spring has morphed into this:
Nowhere have the consequences of the failure been so profound or the costs so high as in Syria. More than a quarter-million people have died. Half the population has been driven from their homes. The world’s worst refugee crisis has overwhelmed neighboring countries and fueled an unprecedented influx of migrants to Europe.
7. In Libya, the Islamic State’s black banner rises by the Mediterranean, by Missy Ryan
In the time after Moammar Gaddafi was removed from power, the Islamic State has built a stronghold in the region. Sirte, the hometown of Gaddafi, today is "a subdued, fearful place, residents say, where the streets are deserted after dusk. Militants have closed banks and schools. Music and smoking are outlawed, and violations of minor rules are met with fines or beatings. More ominous, Islamic State fighters have shown levels of violence previously unseen in Libya."
A teenager from Texas tries to join the Islamic State, makes it to Turkey, but then calls his father and says: "I want to come home." 19-year-old Asher Abid Khan does make it home, but now faces up to 30 years in prison. He is one of several dozen to have been arrested or charged in the United States for allegedly supporting the group.
Before trying to join the Islamic State, Khan had an exchange with a friend where he asked, 'Where is Isis do you know? Bc i might go early." The exchange between his friend Suied is worth a read:
Note: This post has been updated.
Read more stories about the Islamic State: