Brussels has been hit by a number of deadly explosions, with all signs pointing toward a coordinated terror attack.
It's a shocking turn of events, but for anyone closely observing the city over the past few years, it wasn't exactly a surprise: While the Belgian capital had once been known best as a centre for European culture and politics, its reputation had been tainted recently because of links to extremism and terror plots.
Those links were hammered home just last week, when Belgian authorities finally captured terrorism suspect Salah Abdeslam in Brussels's predominantly Muslim Molenbeek quarter. Abdeslam, 26, was the last known surviving participant in November's attacks in Paris that left 130 people dead. Abdeslam was a French citizen of Moroccan descent, but he had been born in Brussels and later lived there in Molenbeek with his family - including a 31-year-old brother, Brahim, who blew himself up in the Paris attacks.
It had been known for months that Abdeslam had traveled back to Belgium after the attacks, but it was only in the past few weeks that Belgian authorities got a lead and captured him and an alleged accomplice. While the discovery of Abdeslam was touted as a success, it also appeared to show that the number of people involved in the Paris attacks could be far larger than first thought. And worryingly, there were signs that Abdeslam and the network around him had been planning more attacks.
At present it remains unclear if there is any link between the French terror suspect and the attacks on Tuesday, but it's not hard to see why many suspect there would be.
A news agency affiliated with Isis said the terror group had carried out the Brussels attacks. AMAQ agency said: "Islamic State fighters carried out a series of bombings with explosive belts and devices on Tuesday, targeting an airport and a central metro station in the centre of the Belgian capital Brussels."
In the wake of the Paris attacks, it quickly emerged that the attackers' suspected ringleader, Abdelhamid Abaaoud, was a Belgian citizen. Abaaoud was killed in a raid in Paris just days after the attack. Brussels was on lockdown for days after it was revealed that Abdeslam had slipped unnoticed through the French border just hours after the attacks in Paris; even after the lockdown was eased, Belgian Prime Minister Charles Michel warned that the threat of an attack still "serious and imminent." Prior to the raid that netted Abdeslam, there were a number of other of raids that uncovered suspected jihadists.
Much of the attention in the aftermath of the Parisian attacks last year focused on French problems such as disenfranchisement and segregation in suburbs and radicalization in the country's prison system. However, it soon became clear that Belgium may suffer from even worse problems.
Molenbeek, an area of northwest Brussels home to around 100,000 people, has emerged as a particular area of concern. "There is almost always a link with Molenbeek,"Michel said last November. "That's a gigantic problem of course."
The area, just across the Canal not far from some of Brussels's more fashionable areas, first began to fill up with Turkish and Moroccan immigrants around 50 years ago. But while the area has seen some levels of gentrification in recent years, it remains a sharp contrast with more affluent areas of the city nearby: Unemployment has been estimated at as much as 40 percent, and there are many seedy and rundown shops in the area.
Often those from immigrant backgrounds find themselves at a competitive disadvantage on the job market as they speak only French and Arabic when many jobs in the city require a knowledge of French, Flemish or Dutch, and sometimes English. A growing right wing political movement in Belgium has led to feelings of division in the country: Some Muslims say that a 2012 ban on Islamic veils like burqas and niqabs in public spaces is a sign of their community's alienation from the Catholic mainstream.
Molenbeek's links to radicalized groups has long been known.
"It doesn't surprise me, because radical and political Islam in Belgium is something that grew up through the years," Bilal Benyaich, a senior fellow at a think tank called the Itinera Institute, told The Washington Post's Steven Mufson last year.
Benyaich pointed to the arrival of funding from Saudi Arabia and other wealthy Persian Gulf states in the 1970s that was used to set up conservative religious schools in the area. A decade ago, Belgian journalist Hind Fraihi went undercover in Molenbeek and wrote a popular newspaper series that showed disillusioned young Muslims were being influenced by radical preachers.
Despite this, the Belgian government failed to act, Fraihi told The Washington Post last year, meaning that "there is a whole generation waiting to participate in these actions."
With the rise of the Islamic State, these ambitions found an outlet. Almost 500 Belgium citizens have traveled to Syria and Iraq during the recent conflict and most end up fighting with the Islamic State, making the country the biggest known exporter of foreign Islamic State fighters in Europe. A group called Sharia4Belgium, led by a charismatic preacher called Fouad Belkacem, has been accused of being at the center of attempts to recruit foreign fighters. Other potential recruits, weary of life in Europe, have made their own links to the group online.
While most of these fighters either remain in Syria and Iraq or have died in the fighting, others are known to have returned to Europe. Authorities believe around 100 may have returned, including Abaaoud, the Belgian citizen believed to be the ringleader in the Paris attacks.
The threat posed by these fighters and others who sympathize with the Islamic State's cause has proven difficult for Belgian authorities to contain. The problem isn't just the sheer numbers of potential jihadists: Belgium is also known as a regional hub for gun smugglers and the country's bilingual government and culture has created problems for investigators.
"Belgium is a federal state and that's always an advantage for terrorists," Edwin Bakker, professor at the Centre for Terrorism and Counterterrorism at the University of Leiden in the Netherlands, told Reuters in November. "Having several layers of government hampers the flow of information between investigators."
There had been hope that Brussels could put its links to terror behind it. A recent tourism campaign for the city had asked interested foreigners to speak on the phone to random residents, most of whom were happy to talk about the city's benefits. One of the phone booths that foreigners could call was even in Molenbeek. However, these attacks show just how difficult it has been for Brussels to contain the threat of terror.