JTA, your original question is a good one. There exists no international consensus in the definition of terrorism, which makes UN resolution 1373 basically useless.
Resolution 1373 describes in broad terms steps to be taken by States to freeze terrorist assets and financial networks, control arms and technology sales and transfers, control immigration, etc., etc.
But in the absence of agreement as to what exactly constitutes terrorism, how can they effect it properly?
More here:
http://www.unodc.org/unodc/terrorism_definitions.html
Quote:
Proposed Definitions of Terrorism
1. League of Nations Convention (1937):
"All criminal acts directed against a State and intended or calculated to create a state of terror in the minds of particular persons or a group of persons or the general public".
2. UN Resolution language (1999):
"1. Strongly condemns all acts, methods and practices of terrorism as criminal and unjustifiable, wherever and by whomsoever committed;
2. Reiterates that criminal acts intended or calculated to provoke a state of terror in the general public, a group of persons or particular persons for political purposes are in any circumstance unjustifiable, whatever the considerations of a
political, philosophical, ideological, racial, ethnic, religious or other nature [*] that may be invoked to justify them". (GA Res. 51/210 Measures to eliminate international terrorism)
3. Short legal definition proposed by A. P. Schmid to United Nations Crime Branch (1992):
Act of Terrorism = Peacetime Equivalent of War Crime
4. Academic Consensus Definition:
"Terrorism is an anxiety-inspiring method of repeated violent action, employed by (semi-) clandestine individual, group or state actors, for idiosyncratic, criminal or political reasons, whereby - in contrast to assassination - the direct targets of violence are not the main targets. The immediate human victims of violence are generally chosen randomly (targets of opportunity) or selectively (representative or symbolic targets) from a target population, and serve as message generators. Threat- and violence-based communication processes between terrorist (organization), (imperilled) victims, and main targets are used to manipulate the main target (audience(s)), turning it into a target of terror, a target of demands, or a target of attention, depending on whether intimidation, coercion, or propaganda is primarily sought" (Schmid, 1988).
[*] How about economic coercion?