Or, to widen the possibilities somewhat, by Cuban interests who would prefer to not have normalized relations with the US, and who could enlist technically-advanced outside help — perhaps from Russia, but not necessarily the Russian government, directly.
One reason a Cuban entity might not want normalization is that a lot of property was taken over during the Revolution, and US Cubans (and other former property owners) have been clear about wanting it back.
Hmm, even though that's a bit of a stretch that actually makes sense. Also Russia seems like the only geo-political adversary that could pull this off and have a vested interest in keeping Cuba in their sphere.
After the Trump administration reversed the previous administrations opening of Cuba, Russia has increased diplomatic relations with the island nation. The trade between the two has doubled
One reason a Cuban entity might not want normalization is that a lot of property was taken over during the Revolution, and US Cubans (and other former property owners) have been clear about wanting it back.
Basic background: https://www.panoramas.pitt.edu/news-and-politics/property-ri...