How the Strait of Hormuz Closure Drove Plastic Prices to Four-Year Highs Across Asia

When the Strait of Hormuz effectively closed in late February 2026, the world focused on oil prices. But the real economic shock for billions of Asians came from something less visible: the price of plastic. The waterway — through which roughly a fifth of the world's seaborne oil and LNG normally passes — is also the primary artery for naphtha, the essential feedstock for Asia's petrochemical industry. Within weeks, plastic resin prices hit four-year highs, and even after a US-Iran peace deal in June 2026, the recovery has been partial and slow.

The naphtha disruption: why Asia was uniquely vulnerable

Asia depends on Middle Eastern naphtha to an extent that has no parallel. According to ICIS data, approximately 80% of Asia's seaborne naphtha imports came from the Middle East before the crisis . When Iran effectively closed the Strait of Hormuz within days of the US-Israel military campaign beginning on 28 February 2026 , that supply line was severed almost overnight.

The problem was not just oil — it was that no viable alternative source of naphtha existed at scale for Asia. Even when Brent crude corrected 23% from its peak in late March, polymer prices kept rising because the physical feedstock shortages persisted .

From naphtha shortage to plastic price surge

The supply chain dominoes fell quickly:

• Naphtha refining margins surged. By early March 2026, the benchmark naphtha refining margin in Asia hit a four-year high of ~$173 per ton over Brent crude as buyers scrambled for alternative supplies . The Platts CFR Japan naphtha marker jumped $78.875 per metric ton in a single session to $715.50 per metric ton on March 3 .
• Plastic resin prices followed. Polyethylene (PE) and polypropylene (PP) — primary plastic resins — jumped to roughly four-year highs in March 2026 . Some market reports indicate polymer prices surged 35–70% within weeks of the closure , with research house Kenanga reporting resin prices spiked by approximately 80% since February 2026 .
• Downstream impact across Asia. Plastic bags, cups, containers, and food packaging became significantly more expensive. At Taipei's Songjiang market, chicken vendor Li Yu-ping reported in early June that the price of plastic bags had jumped nearly 60%, while plastic trays cost a third more . Chinese suppliers raised plastic prices by about 15%, citing heightened raw material costs and overall market instability, according to a CNBC report in March .

A key mechanism drove this divergence: even when crude oil prices fell, polymer prices kept rising because there was no substitute for Middle Eastern naphtha. The Strait's closure disrupted nearly 1.2 million barrels per day of global naphtha export flows , and ADI Analytics estimates that approximately 1.2 million barrels per day of naphtha transits the Strait of Hormuz .

The US-Iran deal: what was agreed

On 15 June 2026, the US and Iran announced a framework agreement (a memorandum of understanding) to end the war and reopen the Strait of Hormuz . President Trump announced via social media that an interim ceasefire agreement would lead to the reopening, saying he had authorized "the immediate removal of the United States Naval blockade" on Iranian ports . A formal MoU was signed on 17 June 2026 .

Oil prices fell more than 4% on the news, and Asian chemical-sector shares rallied sharply . Brent crude futures tumbled below $84 per barrel .

Why the recovery is partial and slow

Despite the deal, plastic prices across Asia have not returned to pre-crisis levels, and experts caution that full recovery will take months.

• Physical flows will take months, not days, to normalize. Allianz Research describes the reopening as a "multi-month process, not a switch," projecting only 80% flow recovery within four months, with full normalization by end of 2026 .
• S&P Global noted that crude markets are expected to remain "tight through the summer months" even after the deal .
• Asian petrochemical prices fell following the deal, but ICIS warned that producer margins remain under pressure as demand recovery lags supply restoration .
• Shipping activity is still far below pre-conflict levels. As of late June 2026, vessel owners and underwriters were waiting for formal demining plans and confirmed channel safety guarantees . The strait has only entered a "semi-recovery phase" .
• Economic scars remain. The New York Times and other outlets report that while relief is coming, Asia's economy and plastics supply chain are unlikely to return to normal immediately — some experts say it could take up to a year for the region to fully recover .

As of 28 June 2026 — just 11 days after the deal — a Moneycontrol report shows that food vendors across Asia were still grappling with elevated plastic costs, suggesting price relief has not yet reached end-users .

What this means for Asia's supply chain

The 2026 Strait of Hormuz crisis exposed a critical vulnerability in the global plastics supply chain: Asia's overwhelming dependence on a single chokepoint for naphtha. Without viable alternative feedstocks, even a temporary closure of the strait can cascade into months of elevated prices for everything from food packaging to auto parts.

For businesses and consumers in Asia, the key takeaway is that even with the strait reopened, the path to normal plastic prices is measured in months, not days. The Allianz Research timeline projects full normalization by end of 2026 , while other analysts suggest recovery could stretch into 2027 .