Secretary of State Marco Rubio is either the luckiest or the shrewdest member of the Trump cabinet —maybe both. His good fortune has been that President Donald Trump has handed the most intractable diplomatic problems — ending the U.S.-Iran and Russia-Ukraine wars — to someone else: special envoys Steve Witkoff and Jared Kushner and, in the case of Iran, to Rubio’s presumed rival for the 2028 Republican nomination, Vice President JD Vance. Neither set of negotiations is showing much progress, but Rubio escapes the fallout.