A: A patent covers, and provides the right to stop someone from making, using, offering or selling
patented invention within the United States. 35 U.S.C. § 271(a). Therefore, if any substantial portion of the action occurs in the US, your US patent should provide a right to sue. It becomes more complicated if only a portion of the invention is made/sold in the US.
The Patent Cooperation Treaty (PCT) opens an opportunity to obtain further rights in foreign jurisdictions. For instance, if your product or process is made in one foreign country and exported to another, you would require a patent in at least one of those foreign jurisdictions to enforce your rights.