Four men launched attacks in Brussels on Tuesday, killing at least 32 people.
Three suspects were killed in the blasts, and one is thought to be on the run.
Two of the suspected attackers were brothers with criminal records.
Turkish authorities warned last year that one of the bombers had tried to cross into Syria.
Suspects may also be linked to Paris attackers.
Belgian authorities on Wednesday stepped up the manhunt for a key suspect in the worst terror attacks in the country’s history, as news emerged that they had previously been warned about another suspect by the Turkish government.
Four men on Tuesday attacked Brussels’ main airport and a train station in the capital, killing at least 32 people and injuring about 260 others. The self-described Islamic State has claimed responsibility for the attacks.
Belgian prosecutors confirmed on Wednesday that they had identified two of the three suicide bombers as Belgian brothers Khalid and Ibrahim El Bakraoui.
Belgian media outlets identified the third suicide bomber as Najim Laachroui. Authorities have not officially confirmed those reports.
Officials believe a fourth suspect, whose image was captured on CCTV at the airport, was able to escape and are continuing a nationwide manhunt for him that started on Tuesday.
Police conducted raids across the country and asked the media not to report any specific details of the searches.
Turkish President Recep Tayyip Erdogan said Wednesday that Turkish authorities had caught Ibrahim El Bakraoui, 29, last year near the Syrian border. Turkey deported him to the Netherlands and warned both Dutch and Belgian authorities that the man was a foreign fighter, according to Erdogan.
It's not clear when El Bakraoui was handed over to Belgian authorities, but according to Reuters, he was later released because "no links with terrorism" were found.
Belgian Minister of Justice Koen Geens said that El Bakraoui was not extradited from Turkey to Belgium. "At that time, the man was not known [in Belgium] for terrorism. Turkey sent him to the Netherlands, not to our country."
The Hunt Is On
Fingerprints found at the crime scene in the Maelbeek subway station allowed investigators to identify Khalid El Bakraoui, 27, as the terrorist who blew himself up in the second car of a train leaving the station.
Khalid’s brother, Ibrahim, was identified as one of the two suicide bombers at the airport.
On Tuesday, police had released a still of security camera footage showing three men at the airport, indicating they were considered suspects. The man on the left is thought to be the third, still unidentified, suicide bomber. Ibrahim El Bakraoui is the man in the middle.
The suspect on the right, in the white jacket, is still on the run. He left the largest quantity of explosives at the airport in a backpack, but they never detonated.
Several media outlets early on Wednesday identified the man on the run as Laachroui, a 24-year-old Belgian national who was born in Morocco. Some even said Laachroui had been detained in Brussels, but later retracted that report. Belgian prosecutor Eric Van der Sypt formally denied Laachroui had been arrested.
Later, sources told public broadcaster VRT that Laachroui was actually the second suicide bomber at the airport. Authorities have not officially confirmed that news.
Police had been searching for Laachroui, who they say may have made suicide vests used in the Paris attacks. His DNA was found on suicide vests in a Brussels apartment connected to other terrorists, a French police official told The Associated Press.
Laachroui had traveled to Syria in 2013 to help recruit fighters for the Islamic State group, authorities said.
A Place Extremists Can Exploit
Belgium is home to a significant number of Islamist extremists, and some of them are connected to militant cells across Europe. While tens of thousands of foreign fighters from multiple countries have joined extremist groups in the Middle East -- including the so-called Islamic State -- Belgium is the European nation that exports the highest number of militants per capita.
French officials criticized Belgian counterterrorism efforts in the wake of the Paris attacks last year. “The Belgians just aren’t up to it,” a former French intelligence official told local press at the time.
Erdogan's comments on Wednesday have raised fresh questions about the capacity of Belgian security services to track down radicalized citizens and prevent attacks. While all European security services need more resources and better coordination to disrupt extremist networks across the continent, Belgium faces some particular challenges, says Petter Nesser, senior research fellow with the Norwegian Defense Research Establishment.
The small country is divided by language and hampered by notoriously complex institutions -- Brussels has six different police districts, for example.
Belgium's black market for weapons, combined with integration and socioeconomic problems in neighborhoods high immigrant populations, make the country a "place that jihadists can exploit for their purposes," Nesser told The WorldPost.
Some experts say Belgium is seen as the "weakest link" in European counterterror operations.
Bomber Brothers Had Criminal Records
The El Bakraoui brothers were well known to Belgian authorities, though more for their criminal records than their extremist beliefs.
Belgian newspaper De Standaard reports that Ibrahim El Bakraoui was believed to have taken part in the violent robbery of a currency exchange office in January 2010. Khalid El Bakraoui was convicted in 2011 for a series of carjackings.
The newspaper adds that Khalid El Bakraoui had reportedly rented an apartment in Brussels that was raided last week as part of the probe into the Paris attacks.
Belgian police searched the apartment in Brussels' Forest neighborhood last Tuesday, looking for clues about the Paris suspects’ locations. They believed the apartment was empty, and were taken by surprise when inhabitants opened fire, wounding four officers.
Mohamed Belkaid, a 35-year-old Algerian suspected of aiding in the Paris attacks, was killed in the raid. Belgian officials said at least two suspects fled the scene. Police found weapons, ammunition and an ISIS flag at the scene, as well as the DNA of Salah Abdeslam, who was previously thought to be in Syria.
Abdeslam was finally captured on Friday, after a four-month manhunt. Police tracked his location using cell phone data and descended on an apartment in Brussels' Molenbeek neighborhood — just 300 meters from the home he grew up in.
In addition to the Forest connection, Khalid El Bakraoui was also allegedly involved in renting a safe house in Charleroi, Belgium, used by the Paris plotters. “If the information about the brothers is right, than there is an official link between the attacks in Paris and those in Brussels,” De Standaard said.
"Always On The Run"
Prosecutors said on Wednesday that investigators found what may be a will written by Ibrahim El Bakraoui in the trash during a raid in the Brussels neighborhood of Schaerbeek.
The note read: “Always on the run, not knowing what to do anymore, being looked for everywhere, not being safe any longer and that if he waits around any longer he risks ending up next to the person in a cell."
At the Schaerbeek apartment, investigators also found chemicals, an improvised explosive device loaded with nails and an ISIS flag.
A taxi driver who had taken the suspects to the airport on Tuesday led police to the apartment. The driver became suspicious after his passengers prevented him from helping to carry their luggage.
The mayor of Schaerbeek, Bernard Clerfayt, revealed on Wednesday that a local police officer had opened an investigation into the tenants of the apartment after receiving a complaint about them. Clerfayt said the investigation hadn't been finished yet.
Victims From Around The World
The victims came from all over the world, with around 40 different nationalities represented among those killed and injured, Belgian Health Minister Maggie de Block said on Wednesday. One of the first victims named was Adelma Marina Tapia Ruíz, a Peruvian-Belgian mother of two, the Peruvian government said. She was on her way to New York to visit her mother.
Belgium observed a moment of silence at 11 a.m. local time to honor the victims of the tragedy. Brussels' airport will remain closed for passenger flights through Friday, airport management said on Wednesday.
Vice President Joe Biden offered support during a visit to the Belgian Embassy in Washington, D.C. on Wednesday. He told the Belgian ambassador to the U.S., Johan Verbeke, that America would “provide any and all information, capability, technology, anything we have that can be value-added to their fight. And they will prevail.”
The White House tweeted the following statement from President Barack Obama after the attacks:
A spokesman for the State Department said Wednesday that some Americans who may have been present during the attacks were still unaccounted for. Nine Americans are known to have been injured, including three Mormon missionaries and a U.S. Air Force officer.
Relatives of Justin and Stephanie Shults, an American husband and wife living in Brussels, told NBC News that they hadn’t been able to track the couple down.
Charlotte Alfred and Nick Robins-Early contributed reporting.
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