WASHINGTON, D.C. — More than two months into a war that has failed to deliver a decisive military or diplomatic win, United States President Donald Trump faces the risk that a standoff with Iran would drag on indefinitely and leave an even bigger problem for the US and the world than before he launched the conflict.

With both sides outwardly confident they hold the upper hand and their positions far apart, there is no obvious off-ramp in sight, even as Iran submitted a fresh proposal to restart negotiations. Trump quickly rejected it on Friday.