BRUSSELS — European Commission President Jean-Claude Juncker has called for a European "security union" to face the threat of terrorism.

His comments come in the wake of Tuesday's terrorist attacks in Brussels and on the day EU justice ministers converged on the city for an emergency meeting to discuss the aftermath of the explosions that struck at the heart of the EU.

Thirty-one people died in the attacks on the city's airport and subway, and more than 250 others were injured.

Speaking on Wednesday, Juncker said Europe needs to do a better job of coordinating its response.

"We feel we need capital markets union, energy union, economic and monetary union, but we also think that we need a security union," he said. "We need everything that will allow us to achieve a security union."

Italy's Prime Minister Matteo Renzi called Tuesday for a "European pact for freedom and security."

"Today they hit Belgium, but they also hit the capital of the European Union," Renzi said in a speech, vowing that "it will take months, perhaps years, but we will beat them."

The demand for a security union comes in the wake of a series of serious intelligence blunders in the runup to the attacks in Brussels.

Turkey's President Recep Tayyip Erdogan said Belgium failed to track Ibrahim El Bakraoui, a convicted Belgian armed robber who Turkey deported last year and who blew himself up at the airport Tuesday an hour before his brother Khalid, a fellow convict, killed at least 20 people at Maelbeek metro station in the city center.

The third bomber, Najim Laachraoui, is a veteran Belgian Islamist fighter in Syria who is also suspected of preparing explosive belts for the Paris attacks in November.

It is also reported that the Islamic State group had sent 400 fighters from Syria to Europe, where it is argued they can move freely across the continent with the aim of carrying out terror attacks.

In theory, a security union would help prevent such lapses, but Juncker's demand was immediately attacked by UK Independence Party MEP Mike Hookem, his party's defense spokesman, who said: "Juncker must be literally mad if he thinks people will sign up to a security union with the EU after it has shown itself dangerously incompetent on this issue."

Alexander Ritzmann, a senior research fellow at the Brandenburg Institute for Society and Security who has worked in the area of counterterrorism for many years, questioned the capacity of the intelligence agencies to address the issues relating to Islamic extremism, religious radicalization and violent extremism.

He said he was "amazed" that 15 years after the 9/11 attacks on the Twin Towers in New York, the West still "did not seem to understand" that terrorism was merely a "tactic" to achieve a specific objective.

"These people do these things not just to kill people — they want a reaction from us," he said.

It has also emerged that Belgium is set to become the latest member state to reintroduce border controls in the wake of the attacks. The country's prime minister, Charles Michel, has asked for the temporary reintroduction of border controls at its internal borders from March 24 up to April 12.

Six other members of the  EU's Schengen passport-free zone have introduced new border controls in recent weeks, largely in response to the migrant crisis that threatens to engulf the continent.

On Thursday, as EU justice ministers gathered in Brussels for an emergency meeting to discuss the aftermath of the attacks, the city remained on high alert, with security further increased for a visit to Brussels on Friday by US Secretary of State John Kerry.

Meanwhile, NATO Secretary-General Jens Stoltenberg has condemned "in the strongest terms" the terrorist attacks.

"Brussels is the home of NATO headquarters and the capital of Belgium and Europe. It is also a symbol of a Europe whole, free and at peace. We will defend our values against the callous acts of those who seek to strike against them. We are resolute in our determination to prevent and defeat terrorism. We will do this by standing together, as open societies and as democracies," he said.

In honor of the victims, a minute of silence was observed outside NATO headquarters in Brussels on Wednesday and the flags of its 28 member nations have been lowered to half-mast.

Martin Banks covered the European Union, NATO and affairs in Belgium for Defense News.

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