*Question E1A11:
[97.5] What licensing is required when operating an amateur station aboard a US-registered vessel in international waters?*  

*Correct Answer is  B: Any FCC-issued amateur license*  

### AI Response: (may contain errors)  

When operating an amateur station aboard a US-registered vessel in international waters, the correct answer is:

**B: Any FCC-issued amateur license**

### Explanation:

1. **Why the correct answer is correct:**
   - The FCC rules allow any holder of an FCC-issued amateur radio license to operate an amateur station on a US-registered vessel in international waters. This is because the vessel is considered an extension of US territory, and thus, US amateur radio regulations apply.

2. **Why the other choices are incorrect:**
   - **A: Any amateur license with an FCC Marine or Aircraft endorsement**  
     - This is incorrect because there is no requirement for a Marine or Aircraft endorsement to operate an amateur station on a vessel. Amateur radio licenses do not have such endorsements.
   
   - **C: Only General class or higher amateur licenses**  
     - This is incorrect because Technician class licensees are also permitted to operate in this scenario. There is no restriction to General class or higher.
   
   - **D: An unrestricted Radiotelephone Operator Permit**  
     - This is incorrect because a Radiotelephone Operator Permit is not required for amateur radio operations. It is typically required for commercial radio operations, not amateur radio.

### Useful Rule of Thumb:

- **US-registered vessels in international waters**: Any FCC-issued amateur license is sufficient for operation, as the vessel is considered under US jurisdiction.