"BERLIN—President Trump’s embrace of Russia is causing Europeans to rethink their security and giving currency to an idea the U.S. has long sought to avoid: a nuclear-armed Germany. Friedrich Merz, who is poised to become Germany’s next chancellor, said Berlin should start talks about expanding the French and British nuclear deterrents to cover Europe, according to an interview the conservative politician did with the Frankfurter Allgemeine Sonntagszeitung weekly. .... On the nuclear side, researchers and some politicians say Berlin’s fastest route to rebuilding a deterrent could be to replicate its arrangement with the U.S. This could see French nuclear bombers...