When Syrian opposition activists pushed John Kerry to take a tougher line with Russian president Vladimir Putin last year, the secretary of state asked them, "What do you want me to do, go to war with Russia?"

When Syrian opposition activists pushed John Kerry to take a tougher line with Russian president Vladimir Putin last year, the secretary of state asked them, "What do you want me to do, go to war with Russia?"

If there is one thing on which Democrats and Republicans can agree, it is that it is undesirable for countries other than the United States to possess nuclear weapons. For this reason, America’s nonproliferation policy has traditionally been characterized by strong bipartisanship. It is notable,…