The desire to return annexed territories may not be per sé something bad, despite the fact it cannot be considered as a natural and spontaneous behaviour in kids, who hardly ever know where are the borders of their country. It is the violence promoted by the state and aimed at creating people ready to hate and fight that cannot lead to anything good, especially when this is realized without creating a discussion about the topic, but just pushing slogan into kids' heads and demonizing any alternative point of view.
NGO should create a dialogue around it, letting the younger generations understand where the problem lies and developing a proper, rational awareness about it. Aware citizens are always to be preferred in comparison with indoctrinated ones, in my humble opinion