Iran, the U.S. and other world powers are nearing a deal to revive the 2015 nuclear accord, although negotiators are still wrangling over significant final demands from Tehran, including the scope of sanctions relief. An agreement could be finalized in Vienna within the next couple of days, said officials involved in the talks. President Biden has made restoring the agreement a top foreign-policy goal. The White House views an agreement restraining Iran’s nuclear program as key to Middle East stability, allowing the U.S. to focus on China and Russia. An agreement would set out the steps Iran and the U.S....