BY A STAFF REPORTER: Australia will buy five U.S. nuclear-powered submarines in the coming years instead of its old diesel-powered submarine fleet, and then collaborate with Britain and the United States to build a new nuclear submarine. National Security Adviser Jake Sullivan said, "By the 2030s, three conventional armed, nuclear-powered ships of the Virginia class will be sold. "The new model, which is nuclear-powered and carries conventional weapons, is a long-term project and will be called SSN-UKUS," he said. "