What foreign-policy tools does the president have to deal with with international terrorism?

Answer 1

Terrorism is a complex problem, and not one open to simple solutions.

Presuming that we are talking about the USA and its conflict with international terrorists here:

The obvious answer is that the President can use military forces at his disposal to directly attack terrorists and their supporting countries.

However, the full range of diplomatic, economic, and cultural influence tools is also available (and, sometimes much more effective than military options) to be used.

The President can use diplomacy to form coalitions of countries interested in fighting (by various means) terrorists. Economic treaties, embargoes, and financial sanctions can be used against individuals, groups, and countries that engage in terrorist activities (or sponsor such folks). Cultural influence can be used to help raise the USA's public image abroad, which erodes the support for terrorists.

The reality is that terrorism is vulnerable to a wide variety of attacks; however, it is neither quick nor simple to deal with terrorism, as one must deal not only with an elusive target (groups of individuals), but the underlying reasons in the global community which allow such terrorists to spawn, recruit, and survive.

Otherwise, you're just playing Wack-A-Mole, and that never ends successfully.