LONDON (Reuters) – In the United States, two Chechen immigrants are accused of the Boston Marathon bombings. In Canada, a doctoral student at a Montreal university is one of two non-citizens accused this week of plotting to derail a passenger train.

The headlines in North America in the past week echo an issue that authorities have been grappling with for more than a decade: why do a tiny minority of men in immigrant communities in the West appear to be drawn to Islamist violence.

LONDON (Reuters) – In the United States, two Chechen immigrants are accused of the Boston Marathon bombings. In Canada, a doctoral student at a Montreal university is one of two non-citizens accused this week of plotting to derail a passenger train.

The headlines in North America in the past week echo an issue that authorities have been grappling with for more than a decade: why do a tiny minority of men in immigrant communities in the West appear to be drawn to Islamist violence.