Interesting question. Article VIII of the Outer Space Treaty [1] states:
> A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or component parts found beyond the limits of the State Party to the Treaty on whose registry they are carried shall be returned to that State Party, which shall, upon request, furnish identifying data prior to their return.
It is clear, then, that the sample containers are still the property of the US, and that if the Chinese brought them back to Earth, they would be required to give them to the US.
They should do that anyways, plus their own, and then they can be like, “when America couldn’t afford it, we stepped in for them because were good people” and it would be strictly a PR win. As long as America didn’t just destroy the sample out of spite later, they could also act nicely and maybe we’re could all get along better.
> A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or component parts found beyond the limits of the State Party to the Treaty on whose registry they are carried shall be returned to that State Party, which shall, upon request, furnish identifying data prior to their return.
It is clear, then, that the sample containers are still the property of the US, and that if the Chinese brought them back to Earth, they would be required to give them to the US.
[1] https://www.unoosa.org/unoosa/en/ourwork/spacelaw/treaties/o...