After the Ursa Major sank off Spain’s coast last Dec, a Russian spy vessel parked over the wreck for 5 days before more underwater blasts were detected, CNN reports. Investigators believe Russia was trying to destroy evidence of its cargo: 2 submarine nuclear reactors bound for North Korea. https://edition.cnn.com/2026/05/12/world/a-russian-ship-sank-in-mysterious-circumstances-it-may-have-been-carrying-nuclear-reactors-to-north-korea
The US twice sent a WC-135R "nuke sniffer" aircraft over the wreck, flight records show. The incident "may mark a rare and high-stakes intervention by a Western military to prevent Russia from sending an upgrade in nuclear technology to a key ally," says CNN.