The Korean currency fell markedly past the 1,500-won level against the U.S. dollar Thursday as global oil prices surged amid intensifying tensions in the Middle East. The won opened at 1,505 per dollar, down 21.9 won from the previous session, breaching the psychologically and technically critical 1,500-won threshold. On Monday, the won touched the level for the first time since March 2009 in intraday trading amid surging global oil prices, the Middle East crisis and concerns about supply disruptions. The weakness came as global oil prices rose more than 5 percent on Wednesday (U.S. time), following Israel's attack on natural gas facilities linked to Iran's South Pars field, the world's largest gas field. In response, Iran's Revolutionary Guard threatened to target oil and gas facilities in Qatar, Saudi Arabia and the United Arab Emirates, heightening the risk of further disruptions to energy supplies, according to foreign media reports. Korea's foreign exchange and stock markets have shown heightened volatility since the beginning of this month following the U.S.-Israeli attacks on Iran.