Efforts to clear naval mines from the Strait of Hormuz could take up to 50 days, potentially delaying the resumption of normal shipping traffic despite an agreement to reopen the strategic waterway, according to maritime security sources and industry officials.

The Strait of Hormuz, a vital chokepoint that previously handled around 20 percent of the world’s daily oil and liquefied natural gas supply, has been effectively blocked since an attack by the United States and Israel on Iran on February 28. The blockade has contributed to tightening global oil supply, with stockpiles in major economies nearing their lowest levels in over two decades.

Five Western maritime security sources estimate that thorough mine-clearing operations, which involve a combination of conventional minesweepers and advanced underwater drones, could take between 40 and 50 days. Such operations are deemed necessary before insurers, shipping companies, and oil traders feel confident enough to resume transit. “The threat of mines remains a concern immediately as well as down the line,” said Jakob Larsen, chief safety and security officer at shipping association BIMCO, underscoring the risk even as a preliminary deal to reopen the strait was announced on Sunday by the United States and Iran.

Although Iran has not confirmed whether it has deployed naval mines during the conflict, Tehran had previously threatened to lay mines and asserted control over the waterway during hostilities. U.S. officials have indicated the presence of mines and targeted Iranian minelaying vessels. U.S. Secretary of State Marco Rubio told a Senate committee in early June that Iran had mined large areas of international waters in the strait. Similarly, Germany’s navy cited intelligence from the U.S. and British navies identifying mines in four locations, though Germany noted it could not independently verify these locations.

The risk posed by mines has rattled global shipping firms, insurers, and tankers, given that a single mine can cause catastrophic damage. Rene Kofold-Olsen, CEO of ship management company V.Group, highlighted the gravity of the threat, noting that 13 vessels under his company’s management remain stranded in the Gulf.

U.S. Central Command declined to disclose specific operational details but confirmed ongoing efforts to clear mines laid by Iran’s Islamic Revolutionary Guard Corps. Meanwhile, Oman’s Maritime Security Centre issued a caution for vessels navigating near its territorial waters after spotting a suspected floating mine.

Shipping levels have seen a modest uptick in recent weeks, with an average of 12 to 15 vessels transiting daily compared to the 120 to 140 ships that passed through before the war. This increase follows quiet facilitation by Iran and the U.S. during negotiations toward a ceasefire. However, a fully cleared and deemed-safe strait is necessary for a substantial recovery in traffic.

Britain, France, and Germany have deployed warships and minesweeping vessels to support clearing operations in anticipation of the challenges posed by mines. Analysts estimate Iran could possess up to 1,000 naval mines, which would require weeks or months to neutralize if minefields are discovered.

The prolonged mine clearance, coupled with ongoing geopolitical uncertainties, suggests that the resumption of unhindered shipping through the Strait of Hormuz will remain cautious and gradual even after the preliminary agreement to end hostilities.