US blockade of the Hormuz Strait: aims, risks, and potential impact on oil flows

On April 13, the United States began blocking the Strait of Hormuz after peace talks between the United States and Israel in Pakistan over the prior weekend ended without a deal. U.S. Central Command (CENTCOM) said the blockade is intended to prevent ships from entering Iran’s ports and does not apply to vessels not visiting Iran.

Purpose and strategic rationale

Analysts say the move is aimed at shifting the dynamics of the U.S.-Iran conflict by pressuring Tehran to accept U.S. demands to end the war and restore freedom of navigation on a critical sea lane.

In an interview with CNBC, Council on Foreign Relations (CFR) senior fellow Michael Horowitz said the blockade is intended to deprive Iran of financial gains from oil sales routed through the Strait of Hormuz. He added that Iran is also restricting oil exports by other countries along the route.

Horowitz noted that Iran is among the world’s top 10 oil producers, accounting for about 4% of global output, with much of its production sold to China. Stopping Iran’s oil exports could therefore be a significant blow to its economy. However, he said the impact of the blockade on oil prices and freedom of navigation remains unclear.

U.S. capabilities and operational readiness

Horowitz said the U.S. has prepared to implement the blockade by strengthening its naval presence in the region for months. He cited multiple carrier groups redeployed to the Middle East, in addition to the Fifth Fleet stationed in Bahrain. He also pointed to U.S. capabilities in submarines and satellites in the Gulf, which he said would allow Washington to monitor ships entering and leaving Hormuz and intervene against Iranian oil shipments.

At the same time, Horowitz cautioned that the blockade is unlikely to quickly restore traffic through Hormuz, as ships remain wary of potential Iranian missile and torpedo attacks.

Iran’s response and conditions for escalation

Iran had signaled defiance before the blockade began. Iran’s Parliament Speaker Mohammad Bagher Ghalibaf wrote on X: “Enjoy the current gasoline prices. With the so-called ‘blockade,’ you will soon reminisce about $4–5 per gallon.”

Iran has also stated that any approaching warships near Hormuz will be considered a violation of the ceasefire and will be met with retaliatory action. If the blockade fails to meet its objectives, the U.S. may need more direct military action to deter threats to ships.

Negotiation outlook and what the U.S. wants

Horowitz said the negotiation challenge is tied to how both sides define conditions for stopping attacks. “To end this conflict completely, the U.S. must clearly discuss with Iran the conditions under which it would stop attacking, and both sides need to understand at least the conditions under which the U.S. could strike Iran again. If Tehran believes that no matter what they do, the U.S. will still attack, then Tehran will continue fighting and continue to threaten Hormuz. This is indeed a challenging negotiation scenario,” he said.

He also suggested the blockade could be intended to address outstanding Hormuz-related issues as Washington considers withdrawing from the war. “Even if the United States wants to withdraw now, an obstacle would be Iran being able to charge fees for passage. Addressing freedom of navigation through Hormuz is essential before the United States can end the conflict. Washington also sees the blockade as a key element to maximize economic pressure on Iran, hoping Tehran will concede,” Horowitz said.

Cost considerations and U.S. openness to talks

CSIS senior fellow Mark Cancian said the Hormuz blockade is the least costly option for the U.S. currently, provided it does not lead to mutual attacks. “Missile launches cost millions of dollars,” he noted, adding that the money spent on this war to date has already been substantial.

Latest developments indicate the U.S. remains open to negotiating with Iran. In an interview on Fox News aired on April 13, U.S. Vice President JD Vance said the next steps in peace talks depend on Iran. “Whether we continue negotiating, whether a deal is reached, I really think the ball is in Iran’s court. We’ve put many options on the negotiating table,” Vance said.

He emphasized that if U.S. nuclear “red lines” are met, “that could be a very, very good deal for both countries.”