World powers and Iran suspended their efforts to revive the 2015 nuclear accord, reigniting a crisis that’s set to impact already surging oil markets and potentially plunge the energy-exporting Persian Gulf into a new cycle of violence. A pause in the Vienna talks was required due to “external factors,” European Union foreign policy chief Josep Borrell said on Twitter, without elaborating. Borrell said the sides had come very close to agreement but didn’t say when — or if — the negotiations would resume. The rupture follows escalating tensions between the Kremlin and the White House. Russia warned on Saturday that it wanted U.S. guarantees that sanctions imposed over its invasion of Ukraine wouldn’t affect its planned partnership with Iran. Oil prices briefly extended gains on the break in negotiations as traders discarded cautious expectations that the U.S. would eventually lift its sanctions on Iran’s economy and ease an effective […]