Answer:
Expatriate
Step-by-step explanation:
An expatriate is a professional who opts to works in another country other than his or her native country. To be regarded as an expatriate, the worker has to be highly skilled. He or she must be living and working in a foreign country.
An expatriate leaves their country to a different nation to provide specialized labor services, not for any other reason. The US citizen leaving for Singapore will be described as an expatriate. He is highly skilled and knowledgeable on the operations of XYZ corporations. The purpose of him being in Singapore is to offer his expertise to the new branch.