JAKARTA — Rattled by rapid oil price swings in recent months, Southeast Asian economies are on tenterhooks ahead of an OPEC meeting this week that is expected to result in a supply cut to boost prices. The recent plunge in prices — the benchmark Brent crude dipped under $60 a barrel last week — has benefited economies such as Indonesia and the Philippines that are net importers of oil. This is helping to blunt the inflationary effects of currency slides against the U.S. dollar in these countries, which are caught in the crossfire of the U.S.-China trade war. Oil rebounded as much as 5% on Monday after the U.S. and China agreed to a truce in their trade conflict. This latest move follows a 30% slide in crude last month, after it touched four-year highs at the start of October. While nations in the region welcome the break in trade tensions — Singaporean Prime Minister Lee Hsien Loong said on Sunday that he hoped to see the U.S. and China take further “constructive” steps — they have to be prepared for further volatility after the meeting of the oil producing cartel that starts on Thursday.