While the Trump administration has increased economic pressure on Iran to deter the country from obtaining nuclear weapons, President Trump and North Korean leader Kim Jong Un agreed to restart nuclear talks. WSJ’s Gerald F. Seib explains the differences in these two approaches. Photos: AP and Reuters BEIRUT—Tighter new U.S. sanctions have proved more punishing than Iran’s leaders expected, driving Tehran to hit back militarily and breach limits it had agreed to put on its nuclear program. This increasingly confrontational approach aims to raise the costs to the U.S. of its maximum-pressure campaign and to push Western European nations to offer economic relief, according to former Iranian officials and analysts. Iran’s…