Such attacks are of concern to the United States and so a definition is required which allows them to be counted. For those who accept that terrorism is about terrorising people, other questions arise. A few years ago, for example, the Islamic Army in Yemen warned foreigners to leave the country if they valued their lives but did not actually carry out its threat. More recently, a group of Israeli peace activists were arrested for driving around in a loudspeaker van, announcing a curfew of the kind that is imposed on Palestinians. Another characteristic of terrorism, according to some people, is that targets must be random - the intention being to make everyone fear they might be the next victim.
Definitions usually try to distinguish between terrorism and warfare.
In general this means that attacks on soldiers are warfare and those against civilians are terrorism, but the dividing lines quickly become blurred. Several examples are given, such as the 1986 disco bombing in Berlin, which killed two servicemen. The most lethal bombing in the Middle East last year was the suicide attack on USS Cole in Aden harbour which killed 17 American sailors and injured 39 more. A similar question arises with Palestinian attacks on quasi-military targets such as Israeli settlements. If, under the state department rules, Palestinian mortar attacks on settlements count as terrorism, it would be reasonable to expect Israeli rocket attacks on Palestinian communities to be treated in the same way - but they are not.