The Franco-Belgian border was closed after the attacks in Brussels that killed at least 34 people and injured over 130 others, and leaders are now calling for more border control.
"Additional security measures will be put into place, restrictions on public transportation, and border control," said the Belgian Prime Minister Charles Michel.
France, the United Kingdom, Germany and the Netherlands also escalated security hours after the attacks.
France deployed 1,600 officers to control the borders, transportation and infrastructure, said Interior Minister Bernard Cazeneuve. Since the Paris attacks on Nov. 13, 5,000 police were "entirely mobilized on the borders," and "10,000 people were prevented from entering the national territory," said Cazeneuve.
The French minister also urged the European Union to pass the "passenger name record," a centralized database of all flight information that has been criticized for allowing for far-reaching surveillance.
Europe's far right and U.S. Republican presidential hopeful Donald Trump are calling to close more borders in light of the attacks.
Belgian far-right party Vlaams Belang tweeted on Tuesday asking the prime minister to close the borders, saying that "we cannot stop terrorism if they stay open!"
"Close the border!"
Marine Le Pen, leader of France's National Front, called for the "real and not fictive closing (of the Franco-Belgian border) like in the past weeks, and the re-establishment of border control on the whole of our national borders."
She added on her party's website that, "We must as of today launch a vast police operation to surround these areas on the margins of the republic and to finally confiscate all arms, war weapons and explosives that are there. We must empty the cellars, laxism has endured for too long."
French Prime Minister Manuel Valls added in a statement that, “We are at war. We have been subjected for the last few months in Europe to acts of war."
Dutch far-right Freedom party leader Geert Wilders added on Twitter, "We have to close our borders and preventively detain and imprison returned Syria fighters. The security of the Netherlands is the most important," and "How long until people recognize Islam is the cause?"
Trump chimed in on Tuesday saying, “I would close up our borders to people until we figure out what’s going on,” he said on Fox News’s program "Fox & Friends. “We don’t know who they are or where they’re from. We don’t learn.”
Ted Cruz, also a Republican presidential hopeful, went on Facebook to say, "Radical Islam is at war with us."
He later took a stronger stance, mimicking Trump's rhetoric adding, “We need to immediately halt the flow of refugees from countries with a significant al Qaida or ISIS presence. ...We need to empower law enforcement to patrol and secure Muslim neighborhoods before they become radicalized.”
British Prime Minister David Cameron of the conservative Tory party said, "We will do everything we can to help." He called for an emergency committee to decide on Britain's response to the attacks.
I am shocked and concerned by the events in Brussels. We will do everything we can to help.— David Cameron (@David_Cameron) 22 maart 2016
Twin attacks, one likely caused by a kamikaze, hit the Brussels airport and a rush-hour metro train in the Belgian capital on Tuesday, triggering security alerts across western Europe. The metro station, Maelbeek, is at the heart of the district of European institutions. Brussels is the capital both of Belgium and the European Union.
Belgian police and combat troops on the streets had been on alert for any reprisal action but the attacks took place in crowded public areas where people and bags are not searched.