European warships have gone into action against people smugglers in the Mediterranean, as French President Francois Hollande warned of the risk of returning to national frontiers, the dismantling of common policies and the abandoning of the euro.
"We need not less Europe but more Europe. Europe must affirm itself otherwise we will see the end of Europe, our demise," Hollande said on Wednesday.
At the same time, German Chancellor Angela Merkel said Europe needed to rewrite its "obsolete" asylum rules to tackle the migrant crisis.
Merkel made the call in a speech with Hollande to the European Parliament - the first such joint address since the fall of the Berlin Wall - in which they urged the increasingly divided EU to unite to tackle a wave of problems including migration and the war in Syria.
"Let's be frank. The Dublin process, in its current form, is obsolete," Merkel said.
The process, which forces frontline states like Italy and Greece to process and welcome most migrants "started from good intentions... but the challenges raised at our borders are from now on untenable".
"I appeal for a new procedure" to redistribute asylum seekers "fairly" throughout the 28-nation bloc, the chancellor said.
Merkel added: "It is exactly now that we need more Europe. We need courage and cohesion, which Europe has always shown when it was necessary."
German authorities on Wednesday said they had registered around 577,000 asylum seekers in the first nine months of the year, a third of whom claim to be Syrian.
Hollande admitted the EU reacted too slowly to the turmoil on its borders since the Arab Spring in 2011, which had produced the huge wave of refugees seeking a better life in Europe.
"I acknowledge that Europe was slow in understanding that tragedy in the Middle East or Africa could not but have consequences for Europe itself," he said.
The French president also gave a dire warning of a regional conflagration in the Middle East that could affect Europe if the world fails to stop the slaughter in Syria, where an uprising against President Bashar al-Assad in 2011 has spiralled into all-out civil war.
"What happens in Syria concerns Europe, what happens there will determine the balance of the whole region for a long time," Hollande said.
"If we leave these religious clashes between Sunnis and Shiites, they will grow. Don't think we will be sheltered, this will be a total war."
The last time the leaders of France and Germany stood together in the parliament was 26 years ago when Francois Mitterrand and Helmut Kohl gave a similar speech just weeks after the Berlin Wall fell.
Meanwhile, the EU formally launched "Operation Sophia" which gives European naval vessels in international waters off Libya the power to stop, board, seize and destroy people traffickers' boats.
Around 3000 people have died making the perilous crossing over the Mediterranean to Europe this year.
The first phase of the operation, which involved monitoring trafficker networks and rescuing refugees from rickety boats, has been running since June.