Should ISIS fighters/wives/children be repatriated?

[Yonadav]

Although a person's service in the armed forces of a foreign country may not constitute a violation of U.S. law, such action could serve as a predicate act for the relinquishment of U.S. citizenship under 349(a)(3) of the INA [8 U.S.C. 1481(a)(3)] under two circumstances. Section 349(a)(3) provides for loss of U.S. nationality if a U.S national voluntarily and with the intention of relinquishing U.S. nationality enters or serves in the armed forces of a foreign state engaged in hostilities against the United States or serves in the armed forces of any foreign state as a commissioned or non-commissioned officer. Note that the administrative presumption of intent to retain nationality does not apply to voluntary service in the armed forces of a state engaged in hostilities against the United States, and thus such action could be viewed as indicative of an intention to relinquish U.S. nationality, although each case is examined on its own with a view to the totality of the circumstances.

https://travel.state.gov/content/travel/...rvice.html