A. chinensis is a quarantine pest within the EU. The recent finding of infested trees in the Netherlands shows that A. chinensis can both establish in Southern Europe as well as in North Western European countries like the Netherlands (it is uncertain if A. chinensis could establish in more Northern parts of the EU). This new information suggests that the overall risk presented by A. chinensis to the EU is greater than previously thought. The probability of introduction is larger than assessed before since many host plants from areas where the pest is present are imported into North Western European countries (e.g. the Netherlands and UK). Also the potential economic and social effects for the whole EU are larger than assessed before. Because of this high probability of introduction and potential major economic and social impacts, there is a need to consider additional measures to reduce the probability of introduction of A. chinensis into the EU. Possible management options and related costs and benefits will be analysed in part 3 of this PRA.