ASEAN Markets Reel as Iran Tensions Threaten 20% of Global Oil Transit

For financial markets, Rubio’s diplomatic mission in Manila is just the tip of the iceberg: the real story is the 20% of global oil that traverses the Strait of Hormuz, now under threat from Iran-linked attacks. Oil prices have rallied sharply, with Brent crude surging past $92 a barrel, squeezing ASEAN’s trade balances and stoking inflation fears. Investors are recalibrating risk, favoring energy stocks and commodity currencies while bracing for prolonged volatility.

The convergence of a renewed Iran conflict, escalating South China Sea tensions, and a high-profile diplomatic push by Washington has thrust Southeast Asia’s energy security into the spotlight. U.S. Secretary of State Marco Rubio’s July 21, 2026, arrival in Manila for the ASEAN ministerial gathering—his first visit to the region in his new role—is not simply a routine diplomatic stop. It is a pivot point where geopolitical rivalry and resource vulnerability collide. The meeting is overshadowed by an active Iran war that threatens the Strait of Hormuz, the narrow waterway through which 20% of the world’s oil supply passes, and by a July 20 confrontation at Second Thomas Shoal that left a Philippine serviceman injured, prompting Washington to demand Beijing ‘immediately cease its destabilizing conduct.’

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Already, Brent crude futures have surged above $92 a barrel, up roughly 12% since the Iran conflict intensified, squeezing government budgets and consumer spending across the 10-member bloc.

Rubio’s stated openness to meeting Chinese Foreign Minister Wang Yi and Russian Foreign Minister Sergei Lavrov on the sidelines reflects the complexity of a region caught between great powers. However, analysts emphasize that Southeast Asian nations are increasingly framing these crises through the lens of energy security rather than military alignment. Peter Cockcroft, director of the Asia-Pacific Net-Zero Institute and former adviser to Philippine presidents, captured the sentiment: ‘The region is not choosing sides, it is diversifying its exposure.’ That diversification is not merely rhetorical. With ASEAN economies heavily dependent on imported fossil fuels—Indonesia, Vietnam, Thailand, and the Philippines all run significant energy trade deficits—a prolonged Hormuz closure could spike oil prices by 50% or more, destabilizing currencies and stoking inflation. Already, Brent crude futures have surged above $92 a barrel, up roughly 12% since the Iran conflict intensified, squeezing government budgets and consumer spending across the 10-member bloc.

The South China Sea adds a second chokepoint dimension. While Hormuz threatens the oil supply from the Middle East, the South China Sea is a critical transit route for liquefied natural gas (LNG) and coal from major producers like Australia and Indonesia. China’s aggressive posture at Second Thomas Shoal, condemned by the U.S., raises fears that any broader militarization could disrupt these lanes, compounding the energy crisis. ASEAN members are thus facing a dual chokepoint squeeze: an active war in the West and a simmering territorial conflict in their own backyard. This reality is reshaping national energy strategies. Malaysia and Vietnam are accelerating offshore gas exploration, Thailand is expanding its strategic petroleum reserves, and regional grid interconnections are gaining renewed urgency under the ASEAN Power Grid initiative.