Iranian and US officials have started a round of high-stakes diplomacy in Oman in what is seen as a last-chance effort to avert a major military escalation in the Persian Gulf. US special envoy Steve Witkoff, who has spearheaded talks for President Donald Trump aimed at ending conflicts from the Gaza Strip to Ukraine, is leading an American delegation in the February 6 talks with Foreign Minister Abbas Araqchi, Tehran's main face on the international diplomatic front, and several other senior Iranian officials. Though the lineups may be set, the…