The CFA charter is a global charter. As such, valid work experience is not limited to the country it which you obtain your charter.
Also, remember that the CFA Institute indicates that you need a U.S. bachelor's degree or equivalent. Although an American degree is used as the standard, most countries around the world offer bachelor's degrees that are equivalent.
For more information on what forms of work experience count as valid experience for you to obtain your CFA charter, click here