Final answer:
A key tool for implementing economic foreign policy is monetary policy, which alongside fiscal policy, helps manage a country's economy and influences international strength.
Step-by-step explanation:
A tool used to implement economic foreign policy is monetary policy, which involves managing the money supply and interest rates. Additionally, fiscal policy plays a critical role, which involves changes in government spending and taxes. These tools can influence the macroeconomy and are integral in maintaining a state's economic prosperity, which is a central component of its foreign policy. Economic sanctions, adjusting trade regulations, and participating in international economic organizations are nonmilitary means that states use to project their power and influence internationally.