A stock broker at the Prudential Brokerage office follows the Hang Seng Index results in Hong Kong in March 2020.Sopa Images | Lightrocket | Getty ImagesAsia-Pacific markets were set to open mixed Wednesday as investors continue to grapple with volatile oil prices, while uncertainty over negotiations between Iran and the U.S. to end the Middle East conflict dents sentiment.Tensions have escalated between Washington and Tehran, with Secretary of State Marco Rubio saying on Tuesday that Iran has mined "large segments" of the Strait of Hormuz."They're firing on commercial ships and they've mined large segments of Hormuz — international waters," Rubio told the Senate Foreign Relations Committee. This marks his first appearance before Congress since the Iran war on Feb. 28.A White House official told CNBC that the Pentagon has destroyed numerous mines and over 40 minelaying vessels. The Strait of Hormuz is a critical waterway, particularly for the energy market globally — around 20% of the world's oil supplies passed through the strait before the war. The West Texas Intermediate futures for June were 1.16% higher at $94.92 per barrel as of 7:45 p.m. ET. Brent crude futures for July last traded at $96 per barrel.Japan's Nikkei 225 was poised to rise, with the Chicago futures contract at 67,305 and its Osaka counterpart last trading at 67,230, compared with the index's previous close of 66,734.24.Hong Kong's Hang Seng index futures last traded at 25,853, lower than the index's last close of 26,038.32.In Australia, futures for S&P/ASX 200′ last traded at 8,789, while the index closed at 8,724.40.Stock Chart IconStock chart icon