The rules regarding rescues at sea and safe ports are spelled out in the Hamburg International Convention on Maritime Search and Rescue, which was ratified by Italy.
The decision to take the 450 migrants from a wooden vessel off of Linosa onto two military ships is linked to the obligation to provide rescue to those who are in difficulty at sea. The requirement is part of the Hamburg International Convention on Maritime Search and Rescue, which is an international agreement aimed at protecting the safety of mercantile shipping.
Known by the acronym SAR, the agreement was signed on April 27, 1979, but Italy ratified it 10 years later, in 1989.
The issue of "place of safety"
The regulations provide for more than just the duty of helping those who are shipwrecked from becoming lost at sea. There is also an obligation, which is closely connected to the first one, to take the shipwrecked people to a so-called "place of safety". According to SAR, a place is "safe" if it guarantees the physical protection of those rescued at sea.
The meaning of a place of safety becomes broader when those who are rescued are migrants. In this case, other requirements come into play that are tied to the need to enact administrative procedures connected to the asylum-seeker status of those rescued.
For Italy, the place of safety is determined by the SAR Authority, the Transport Ministry's Coast Guard Operations Centre, in coordination with the Interior Ministry.
Although there is an international obligation to rescue those who are shipwrecked and to ensure them a "place of safety", there are also Italian laws in the Navigation Code that allow the Transport Ministry to ban access to Italian territorial waters or Italian ports for specific peremptory reasons, including public safety, navigational safety and (although this isn't the case), marine environment safety.
In the first possibility, the Transport Ministry works together with the Interior Ministry, while in the second, it intervenes directly on the report by the Coast Guard, which is responsible for surveillance and control.