South Korean authorities are on heightened alert and signaling possible verbal intervention, as a Middle East-driven oil shock keeps pressure on the won, pushing the dollar-won monthly average toward crisis-era levels. The tougher tone follows the currency’s brief breach of the 1,500-per-dollar mark in Friday overnight trading, renewing concern about volatility in the foreign-exchange market. “Major currencies such as the won, yen and euro are all weakening as the dollar strengthens,” Finance Mi