Only months after Donald Trump became the federal president in the U.S., an idea, “once unthinkable,” was “gaining attention in European policy circles: a European Union nuclear weapons program.” The arsenal in the state of France would be “repurposed”—which is to say, federalized in American terms—to protect the European Union rather than merely one of its states. The command of the weapons, as well as the funding plan and defense doctrine, would be federal. Even though the question of whether the E.U. could continue to count of American protection—there being dozens of American nuclear weapons in the E.U.—was at the time most tantalizing, I submit that the matter of federalism in the case of the E.U. is salient too.
The full essay is at "Federalizing State Warheads in the E.U."
 Max Fisher, “Fearing U.S. Withdrawal, Europe Considers Its Own Nuclear Deterrent,” The New York Times, March 6, 2017.