You could feel the fabric fraying from Jerusalem to Pennsylvania Avenue. Thanks to the prospect of a nuclear Iran, the ties between the U.S. and Israel were under more strain in 2013 year than in any year in recent memory. As the Obama administration pursued negotiations with Iran in an attempt to defuse the Islamic republic’s nuclear intentions, Bibi Netanyahu cried foul — long and loud. A nuclear Iran is an “existential” threat to Israel, he said, and a dangerous prospect as well to moderate Arab states like Saudi Arabia. He blasted the interim deal hammered out in Geneva as “a historic mistake.” And he put American Jews squarely in the middle of the fight at the General Assembly of the Jewish Federations of North America, where he urged participants to lobby against their own country’s diplomatic position.