WASHINGTON — The United States is well on its way toward controlling Iranian airspace, White House press secretary Karoline Leavitt said on Friday, adding that Washington expects the achievable U.S. objectives to be completed in four to six weeks. Speaking to reporters at the White House, Leavitt also said Washington was looking at potential candidates to lead Iran, a day after President Donald Trump told Reuters in an interview that the United States must be involved in choosing the next leader of Iran. "I know there's a number of people that our intelligence agencies and the United States government are looking at, but I won't get any further on that," Leavitt said. In the interview on Thursday, Trump said that he thinks the next leader of Iran is unlikely to be the late Supreme Leader Ayatollah Ali Khamenei's son, who has emerged as a frontrunner to succeed his father, who was killed in a military strike at the start of the war. Earlier on Friday, Trump said there would be no deal struck with Iran except "unconditional surrender." "What the President means is that when he, as Command