Germany, Austria and Italy threaten the EU with a suspension of the Schengen zone, in a repeat of the 2015 domino effect that saw the reintroduction of border controls.

Chancellor Angela Merkel agreed with her interior minister Horst Seehofer on Monday evening to establish “transitional” detention centres along the border with Austria, to facilitate a swift pushback of apprehended migrants.

The idea is to send migrants backs at their point of entry in the EU, as envisaged by the Dublin II agreement.

The President of the European Commission, Jean Claude Juncker, told the press in Strasbourg on Tuesday that although he had not studied the deal, it appeared to be “legally compliant.”

But, two days after Austria assumes the presidency of the EU, the Austrian Chancellor warns that Vienna could respond with the reintroduction of border controls along the border with Italy and Slovenia.

“Should this agreement become the German government’s position, we see that as prompting us to take action to prevent negative consequences for Austria and its population,” Chancellor Sebastian Kurz said.

Austria underscored the point through exercises of its new ProBorder force along the border, in a mock repeat of the December 2015 crisis, the German news agency DW reports.

Hours later, the Italian foreign minister Moavero Milanesi responded that if Austria were to close the Brenner pass, it would have to “assume its responsibilities.”

“The European Council affirmed that immigration is a European issue and we need a shared effort,” he told the public news agency ANSA.

Kurz said on Tuesday that he hoped for a Europe without borders in “the medium to long-term,” noting that Austria would of course honour the migration quotas arrangement.

Meanwhile at least 114 migrants drowned in the third shipwreck in four days off the Libyan coast on Monday, the UNHCR said. Non-Governmental Organizations vessels have been discouraged by Italy and Malta from continuing salvation operations in the Mediterranean.

“There is a difference between rescuing and ferrying,” the leader of the Five Star Movement (MS5) Di Maio reiterated on Tuesday. Following talks with the Latvian President Raimonds Vejonis on Tuesday, Di Maio called NGO ships “migrant taxis.”