On a normal day—any day, really—this would be a stupid question. By law and policy, Washington doesn’t assassinate political officials unless that official works for a government engaging in hostilities against the United States (this is one of the arguments the White House has used in the days after Soleimani’s death, in addition to his designation as an international terrorist). The U.S. got out of the assassination game after the Church Committee uncovered a series of abuses, illegality, and botched policy planning within the intelligence community in the 1970’s, a product that resulted in President Gerald Ford issuing a ban on the tactic via executive order.
Beyond the law, targeting leaders of a nuclear-armed power is insane, the very kind of strangelovian scenario that would likely rush the cabinet to invoke Article 25 of the U.S. Constitution. Never in the history of the United States has an American president believed such an option was a good idea. The reasons are obvious: targeting an official representing a nuclear state would result in the type of extreme retaliation that could quickly spiral into an uncontrollable nuclear exchange. Mutually assured destruction kept the United States and the Soviet Union, two superpowers that at one point had tens of thousands of warheads between them, restrained from going down a cycle of escalation that would be difficult to escape from.