US Centcom says Hormuz blockade will begin Monday and will only apply to Iranian ports; China will be most affected

TOI correspondent from Washington: The US military said it will begin enforcing President Trump-announced blockade of the Hormuz Strait at 10 am EST on Monday (730 pm IST), while clarifying that the embargo will only apply to vessels entering or departing Iranian ports and not other Gulf entrepots.

"CENTCOM forces will not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports," the Tampa-based military command said in statement on Sunday, underlining free passage for countries trading with U.S Gulf allies such as UAE, Qatar, and Saudi Arabia that also use the Strait of Hormuz for trade and commerce. “The blockade will be enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman,” Centcom said.

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Still, President Trump’s decision to impose a naval blockade is being seen not only as an escalation against Iran, but also as a move that edges perilously close to an indirect or de facto declaration of war against China, which is the primary consumer of Iranian crude and the biggest stakeholder in the shadow trade the blockade aims to choke. This is because, as in the case of Russia, Trump believes oil revenues is keeping Iran afloat.

Under international law, a blockade is widely regarded as an act of war, according to legal experts. The principle dates back to customary maritime law and has been codified in various legal interpretations: when a state uses force to prevent ingress or egress of vessels to another state’s ports, it is viewed as engaging in belligerent activity. During the Cuban crisis, Washington deliberately called its blockade a “quarantine” to avoid the legal implication of declaring war on the Soviet Union, but the Trump dispensation has dispensed with such niceties while indirectly taking aim at China.

What elvates the sakes further is China's overwhelming exposure to Iranian oil, with the country accounting for more than 90 percent of Iran’s oil exports, importing roughly 1.5 to 1.6 million barrels per day through a complex sanctions-evasion network. This constitutes approximately 15–16 percent of China’s total crude imports, making Iran one of Beijing’s most critical external suppliers.

The trade itself is said to operate in a legal grey zone. Iranian oil is shipped via a “shadow fleet” of tankers operating under flags of convenience, with frequent ship-to-ship transfers in waters near Malaysia and the United Arab Emirates. Cargoes are often relabeled before being processed in China’s independent “teapot” refineries. Payments are increasingly denominated in yuan, further insulating transactions from U.S. financial scrutiny.

With Western markets closed due to sanctions, China is effectively said to be the sole large-scale buyer sustaining Iran’s export revenues, which currently hover between 1.5 and 1.9 million barrels per day despite wartime disruptions. Severing this lifeline would cripple Iran’s fiscal capacity to sustain both its domestic economy and military posture.

For China, the stakes are equally high. Iranian crude is discounted and losing it would force Beijing into tighter competition for supplies from Saudi Arabia and Russia, likely at higher prices and under less favorable terms. By targeting vessels linked to Iranian exports—especially those suspected of paying transit tolls to Iran’s Revolutionary Guard—the U.S. blockade directly pinches China’s energy supply chain. Beijing has already signaled its displeasure, blaming Washington for triggering the crisis through earlier strikes and warning against “militarization” of global energy routes.

In comparison, New Delhi’s purchase of Iranian oil is negligible. India’s recent resumption of imports from Iran, enabled by a temporary U.S. sanctions waiver, is small and symbolic. A single cargo delivered to Indian Oil Corporation recently marks a tentative reopening rather than a structural shift. Historically, India imported 15–20 percent of Iran’s exports before 2019, but that share went to near zero after sanctions tightened.

India then moved on to Russian oil but even that was whittled down with U.S tariffs amounting to sanctions, forcing it to go further afield to the U.S and Venezuela. If the blockade persists, India’s exposure will remain minimal in direct terms, but it will feel the secondary effects: higher global prices, tighter supply, and increased competition for alternative sources. Also squeezed out by the blockade will be basmati rice, which India exports in significant quantity to Iran.

The most immediate uncertainty lies with other Gulf exporters—Saudi Arabia, the United Arab Emirates, Qatar, and Kuwait—all of whom rely on the Strait of Hormuz to ship their oil and gas. In theory, the U.S. blockade is targeted at Iran, not at commercial traffic from allied producers. In practice, the distinction may prove difficult to maintain. Iran has already demonstrated its ability to disrupt traffic through mines, drone threats, and selective interdictions, all of which could come to an end if the U.S power through and takes control of the Hormuz Strait, in which case President Trump will demand his pound of flesh, as he has indicated.

Till then, the global energy system will be confronting its largest disruption since the 1970s. Estimates suggest that 9 to 11 million barrels per day of supply capacity have been affected by the conflict and the evolving blockade. If the U.S. enforces a strict interdiction regime, Iranian exports could collapse, removing up to 1.5 million barrels per day from the market. But the bigger risk is contagion: a wider shutdown of Hormuz traffic would take far larger volumes offline, triggering a full-scale supply shock.