Common Article 1 to the four Geneva Conventions lays down an obligation to respect and ensure respect for the Conventions in all circumstances. This paper focuses on the second part of this obligation, in particular on the responsibility of third States not involved in a given armed conflict to take action in order to safeguard compliance with the Geneva Conventions by the parties to the conflict. It concludes that third States have an international legal obligation not only to avoid encouraging international humanitarian law violations committed by others, but also to take measures to put an end to on-going violations and to actively prevent their occurrence.
