(a) An aerial blockade may be enforced and maintained by a combination of lawful means of warfare, provided that this combination does not result in acts inconsistent with the law of international armed conflict.
(b) Aircraft in distress must be allowed to enter the blockaded area when necessary.
- An aerial blockade may be maintained by the Blockading Party through the use of any means of warfare not prohibited under the law of international armed conflict. Therefore, an aerial blockade may be maintained and enforced by military aircraft (including UAVs and UCAVs), missiles, warships, or by a combination thereof.
- No category of aircraft other than military aircraft is allowed to participate in maintaining and enforcing an aerial blockade (see Rule 17 (b)).
- Rule 153 (b) is based on Art. 7 of the 1909 London Declaration and on the customary norm — as reflected in UNCLOS — that assistance must be rendered to those who are in distress in the air or at sea.
- As indicated by the words “when necessary”, Rule 153 (b) is not absolute in character. For instance, access to the blockaded area may be denied if there exist equally safe and timely alternatives for the aircraft in distress to land.
- Art. 7 of the London Declaration: “In circumstances of distress, acknowledged by an officer of the blockading force, a neutral vessel may enter a place under blockade and subsequently leave it, provided that she has neither discharged nor shipped any cargo there.”
- There is an affirmative obligation under both customary and treaty law to render assistance to those who are in distress in the high seas, as affirmed in Art. 98 (1) of UNCLOS (“Duty to render assistance”): “(1) Every State shall require the master of a ship flying its flag, insofar as he can do so without serious danger to the ship, the crew or the passengers: (a) to render assistance to any person found at sea in danger of being lost; (b) to proceed with all possible speed to the rescue of persons in distress, if informed of their need of assistance, insofar as such action may reasonably be expected of him; (c) after a collision, to render assistance to the other ship, its crew and its passengers and, where possible, to inform the other ship of the name of his own ship, its port of registry and the nearest port at which it will call.”