What happens to RSX (VanEck Russian index ETF, on CBOE (American) exchange) if owning Russian securities is banned due to sanctions?

It's going to get crushed tomorrow due to market forces but I was more wondering about the mechanics of what happens if owning Russian stock becomes illegal in the US due to sanctions.

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Is that likely to happen and how would it work, would etfs/individuals be forced to sell their holdings by a certain time?

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Thanks!