A visa is not required for US citizens for business or tourism for a stay of up to 90 days in any six month period.
Please keep in mind that while a visa is not required, you must:
- Hold a passport valid at least six months on entry with TWO blank visa pages
- Hold proof of onward/return flights
- Hold all documents required for the next destination
- Hold proof of sufficient funds relative to your intended length of stay.
- Confirm with their airline that boarding will be permitted without a visa.