A major diplomatic breakthrough between Washington and Tehran could signal sanctions relief for Iran, a development analysts say bodes well for China, the primary buyer of Iranian oil.Negotiations have advanced on a proposed 60-day ceasefire extension, the reopening of the Strait of Hormuz and the US side issuing temporary sanctions waivers that would allow Iran to sell oil freely, Axios reported on Saturday, citing a US official. Any such relief would only be implemented under a final agreement, the report added.AdvertisementWashington is likely to loosen its grip on China’s Iranian oil imports, “given that the US-Iran peace talks cannot succeed…