Iran’s nuclear program is the main reason U.S. President Donald Trump said he had to attack the country on Feb. 28. Resolution of the dispute over that program could help move the two sides beyond a ceasefire and toward a negotiated end to the war. Mr. Trump has vowed for years to deliver a “much better” deal preventing Iran from attaining a bomb than what he calls the “disastrous” one concluded under President Barack Obama more than a decade ago. A comprehensive deal ending the Iran war could be the president’s last best opportunity to make good on his pledge. Why We Wrote This In the absence of renewed U.S.-Iran talks, the combatants are wrangling over the Strait of Hormuz. But the main dispute between the two is still Iran’s nuclear program, and President Donald Trump’s pledge to secure a better deal than did President Barack Obama.…