Twenty airlines resumed flights from Brussels Airport and the gate B section fully reopened on Wednesday, a day the Belgian prime minister says marks a "return to normal life."

But normalcy will be a long road forward for Brussels after 32 people were killed in the twin attacks that rocked the Zaventem airport and the city's Maelbeek metro station on March 22.

The first passenger planes to leave the airport since the attacks left large sections of the terminal damage departed on Sunday, but the flight was a symbolic one. 

On Wednesday, the airport reopened gate B, meaning the situation for passengers arriving and departing from the airport is "back to normal" according to the airport. 

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A return to normalcy was the message from Belgian leaders on Wednesday as well, as they chart a plan for the country to move forward from the deadly attacks. 

"Today we return to normal life in Brussels and Belgium," said Belgian Prime Minister Charles Michel, speaking to journalists on Wednesday morning.

Michel admitted that the country had made mistakes in tackling the problem of violent extremism in the country. But he said Belgian officials learned lessons from the attacks and plan to prioritize information-sharing.

Belgium must show the world "it can improve what was a failure and has learned its lesson," Michel said.

Belgian investigators took more than four months to find and arrest key Paris attacks suspect Salah Abdeslam, who had been hiding out in Brussels since the attack. His March arrest pre-dated the attacks by about a week, and investigators believe the men who carried out the attacks were linked to Abdeslam. However Michel defended the arrest and rebuffed critics who say Belgian authorities took took long to apprehend him.

"Some said you need so many months, it is too many," Michel said. But he noted it took nearly 10 years for the U.S. to track down and kill Osama Bin Laden following the Sept. 11, 2001 attacks.

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Travellers passing through Zaventem airport on Wednesday described heightened security measures but a "surprisingly painless experience."

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While arrivals in Brussels' Zaventem Airport have returned to normal, travellers departing from the airport are being processed in a temporary building, due to the damage in the departures hall.

Some shared photos of posters where travellers were writing messages of support for those affected by the attacks. 

The city's metro system is expected to be back to full capacity next week. 

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The bombings, and missed signals in Belgium's investigations of many of those responsible for the Nov. 13 attacks in Paris that killed 130 laid bare numerous failings by Belgian law enforcement and security services.

Belgium's prime minister acknowledged Wednesday that the country has made mistakes in combating violent extremism but rejected the notion that it has become Europe's weakest link in efforts to eradicate the threat.

"In the fight against terrorism, in all countries in the world and in Europe, there have been successes and there have been failures," Prime Minister Charles Michel said.

Additional information from the Associated Press.

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