The immediate concern is how to contain the crisis in Japan's nuclear plants. But thoughts are also turning to the future and, in the world's two big industrial blocs, the politics of nuclear power has already changed.
In Germany, there's already been a long debate about what to do with the country's 17 nuclear power stations. Last October, Chancellor Angela Merkel's government decided, with much opposition, to extend their lives by another 12 years so that the last one is now due to be closed in 2035.
That fractious debate has now reopened. The political difficulty for Mrs Merkel is that support for the Greens had already been rising in her heartland just as important elections take place.
In two weeks, the voters of Baden Wuerttemberg go to the polls. This is her natural territory. It has been controlled by the Christian Democrats for decades but Japan's disaster may now change that.
On Saturday, a previously scheduled anti-nuclear demonstration in the region attracted tens of thousands more than expected. That evening, the chancellor met her ministers to discuss the Japanese events and announced that safety standards in Germany would be reviewed.
But her dilemma is how to answer concerns without undoing her policy.