The relationship between Iran and the U.S. has worsened since the Trump administration pulled out of the Iran nuclear deal and reimposed sanctions. A June 13 attack on two oil tankers that the U.S. blamed on Iran set off a sequence of retaliation. After Iran shot down a U.S. drone, President Trump considered bombing Iran, but called it off at the last minute.
Trump believes the threats of military action combined with the sanctions will force Iran to go back to the bargaining table. Trump wants a tougher new accord. He has said he doesn't want war, but his national security adviser, John Bolton, has been publicly calling for an attack on Iran for more than a decade.