Would it be illegal (under US law) for a US citizen to own slaves in another country?

[hexxie]

Slavery today is illegal in all countries, but if a US citizen owned slaves in another country (possibly where there was little or no enforcement of that law), would that be prosecutable in some form under US law?

Say they owned a company and knowingly used slave labor, or had an underground sexual slavery operation in other countries. Does US Federal law have extraterritoriality in these cases, or could the International Criminal Court become involved?

Do all US Federal laws apply to US citizens overseas? Technically speaking, it’s illegal for Americans to buy Cuban cigars outside of the US, but that law is difficult to enforce. The USA isn’t a party to the International Criminal Court, but under what conditions can the ICC prosecute?

What if the scenario I brought up happened in another non-ICC signatory state, and the country where they owned the slaves had no functional power to lay charges (due to collapse of government or civil war)?

[Nametag]

I don’t see any “within the United States” exceptions here:

18 U.S. Code § 1581 - Peonage; obstructing enforcement

(a) Whoever holds or returns any person to a condition of peonage, or arrests any person with the intent of placing him in or returning him to a condition of peonage, shall be fined under this title or imprisoned not more than 20 years, or both.

18 U.S. Code § 1593A - Benefitting financially from peonage, slavery, and trafficking in persons

Whoever knowingly benefits, financially or by receiving anything of value, from participation in a venture which has engaged in any act in violation of section 1581 (a), 1592, or 1595 (a), knowing or in reckless disregard of the fact that the venture has engaged in such violation, shall be fined under this title or imprisoned in the same manner as a completed violation of such section.

And there’s this:
18 U.S. Code § 1596 - Additional jurisdiction in certain trafficking offenses

(a) In General.— In addition to any domestic or extra-territorial jurisdiction otherwise provided by law, the courts of the United States have extra-territorial jurisdiction over any offense (or any attempt or conspiracy to commit an offense) under section 1581, 1583, 1584, 1589, 1590, or 1591 if—
(1) an alleged offender is a national of the United States or an alien lawfully admitted for permanent residence (as those terms are defined in section 101 of the Immigration and Nationality Act (8 U.S.C. 1101)); or
(2) an alleged offender is present in the United States, irrespective of the nationality of the alleged offender.
(b) Limitation on Prosecutions of Offenses Prosecuted in Other Countries.— No prosecution may be commenced against a person under this section if a foreign government, in accordance with jurisdiction recognized by the United States, has prosecuted or is prosecuting such person for the conduct constituting such offense, except upon the approval of the Attorney General or the Deputy Attorney General (or a person acting in either such capacity), which function of approval may not be delegated.