Can karma operate at the level of groups i.e. collectively?

In the book the Land of No Buddha the author interviews a Tibetan lama in which he talks about collective karma - to quote > All groups have karma that is more than just the collection of the > karma of the individuals of the group. For example a group can decide > collectively to start a war. (pp 76 of above book) This is the first and only time I have heard of collective karma. Is this a concept purely within Tibetan Buddhism? Is it wider than that or is it perhaps just this lama's understanding and it not really a concept in Buddhism generally? If it is a genuine concept then can someone give some more details and perhaps how it fits in with karma at an individual level?