What term describes an insurer that operates in the U.S. but is based outside of the country?

The term that describes an insurer operating in the U.S. but based outside of the country is "alien insurer." This classification applies specifically to insurance companies that are incorporated in another country but conduct business within the United States. The term "alien" is a legal designation used to identify entities that are based outside the jurisdiction in which they are operating.

In contrast, a domestic insurer is one that is incorporated and does business in the state where it is licensed. A foreign insurer is one that is licensed to operate in a state but is incorporated in another U.S. state, rather than in a foreign country. Lastly, "international insurer" is not a specific classification used in U.S. insurance regulation, and thus does not fit the context of this question.

Understanding these definitions is essential in insurance practices, particularly for producers who must navigate various insurance regulations that apply to domestic, foreign, and alien insurers.