The in­ter­im deal be­tween the Unit­ed States and Iran is sup­posed to ush­er in a two-month pe­ri­od that would ad­dress the most di­vi­sive is­sue be­tween the long­time ad­ver­saries — Tehran’s nu­clear pro­gram.

Pre­vent­ing Iran from at­tain­ing a nu­clear bomb is a key rea­son that Pres­i­dent Don­ald Trump said he launched the war along­side Is­rael in Feb­ru­ary, but the ten­ta­tive agree­ment he has trum­pet­ed leaves lit­tle run­way to ne­go­ti­ate the long-run­ning stick­ing point. The pre­vi­ous nu­clear pact be­tween Iran and world pow­ers, from which Trump pulled the U.S. in his first term, took many months to ne­go­ti­ate.

Un­der terms of the ini­tial deal, Iran would im­me­di­ate­ly take steps to re­open the Strait of Hor­muz to glob­al oil ship­ments and would be al­lowed to sell its oil with­out re­stric­tions, U.S. and re­gion­al of­fi­cials say.