Since Greece made a concentrated effort to tighten the border crossing along Turkey, the main entry point for illegal immigrants to Europe, the Aegean islands are now taking the strain.

The decision to set up the four centers, according to Kathimerini, located on Chios, Lesvos, Samos and Rhodes was taken during a meeting on Monday between Prime Minister Antonis Samaras, Defense Minister Panos Panayiotopoulos, Public Order Minister Nikos Dendias and Merchant Marine Minister Costas Mousouroulis in an attempt to prevent immigrants from reaching the mainland before they are deported.

Dendias also presented to Samaras a plan code-named Ioni aimed at dealing with the influx of refugees from Syria, the paper writes.The islands are ill equipped to deal with the mass influx of migrants they warily anticipate, with particular concerns that a flood of Syrian refugees will be smuggled in from Turkey.

According to sources, the plan outlines three scenarios, foreseeing the refugees’ arrival in Greece, Cyprus and Turkey. In either of the latter two cases, Greek authorities would help the neighboring countries. In the event that the migrants arrive in Greece, the plan is to temporarily detain them on Crete. Turkey, meanwhile, is hosting more than 80,000 Syrians who have been fleeing their country’s civil war. There’s been no sign yet of a notable number of Syrians arriving to Greece. But the government in Athens is under pressure to crack down on illegal migration in general.

Earlier this month a Doctors Without Borders/Médecins Sans Frontières (MSF) team visited the Aegean Islands of Samos, Leros, and Simi to respond to reports of a recent influx of Syrian and Afghan migrants and asylum-seekers. According to a report by MSF newly arrived migrants face limited access to health care in Greece. Infrastructure and accommodation capacity is limited and sanitation standards are inadequate in all of the facilities visited by the MSF team, and access to basic resources such as drinking water and in some cases food is limited. Personal hygiene items are unavailable, and currently used transit sites do not have separate facilities for men, women, and families.