Iran struck a historic deal Sunday with the United States and five other world powers, agreeing to a temporary freeze of its nuclear program in the most significant agreement between Washington and Tehran in more than three decades of estrangement. Iranian President Hassan Rouhani endorsed the agreement, which commits Iran to curb its nuclear activities for six months in exchange for limited and gradual sanctions relief, including access to $4.2 billion from oil sales. The six-month period will give diplomats time to negotiate a more sweeping agreement. It builds on the momentum of the public dialogue opened during September’s annual U.N. gathering, which included a 15-minute phone conversation between President Barack Obama and moderate-leaning Rouhani, who was elected in June. ...