President Obama has a proposition for Russia. Remember when he said he wanted to work toward ridding the world of nuclear weapons? Well, he meant it. And he’s willing to take one for the cause as long as Russia does, too. Obama called on the Russian government to join the U.S. in cutting the number of strategic nuclear warheads it deploys. The president will elaborate on his proposal Wednesday at the Brandenburg Gate in Berlin, a historically significant setting along the line where a wall once divided the German city that is sure to evoke memories of the Cold War that enhance Obama’s argument.