Complex sentence: The two governments immediately started complex diplomatic manoeuvres to bring world opinion on their side in the case, as widely expected, that the conflict was resumed; but the two sides were also careful to leave the door open for a peaceful solution.
Split into simpler sentences: The two governments immediately started complex diplomatic manoeuvres to bring world opinion on their side in case, as was widely expected, the conflict was resumed. However, the two sides were also careful to leave the door open for a peaceful solution.