Why Tanker Traffic in the Strait of Hormuz Surged After the US-Iran Peace Deal — Then Came to a Halt

On June 18, US Central Command formally announced the end of the blockade on vessels to and from Iranian ports .

The 14-Point Agreement (Islamabad Memorandum of Understanding)

The MoU is a framework document of fewer than 800 words, described as a 14-point plan . Key provisions include:

• Immediate and permanent cessation of military operations on all fronts, including Lebanon .
• Reopening the Strait of Hormuz for maritime navigation without any tolls imposed by Iran .
• Lifting of the US naval blockade on Iranian ports .
• 60-day negotiation window for a final comprehensive agreement covering Iran's nuclear program, the future of the Strait, and broader normalization .
• Financial relief for Iran (specific dollar amounts were not detailed in public summaries) .
• Iranian commitment to refrain from developing nuclear weapons .
• The agreement does not address Israel's role in detail and leaves many specifics to the follow-on nuclear talks .

The Halt: Cancellation of Switzerland Nuclear Talks

US Vice President JD Vance had been scheduled to travel to Switzerland on Friday, June 19 to meet Iranian negotiators for the first follow-on nuclear talks under the 60-day framework . Switzerland's foreign ministry announced the talks were abruptly postponed, and the White House confirmed Vance's trip was put off . The cancellation came as a surprise; the Irish Times reported Trump had told Israel to "calm down" amid the diplomatic confusion .

While some vessels continued crossing on June 19-20, the diplomatic rupture shattered the confidence needed for a large-scale resumption. Shipowners and insurers, already operating in "wary disbelief," pulled back from committing more vessels . Traffic that had been accelerating rapidly on June 18 essentially flatlined, with only a handful of mostly Iran-linked vessels crossing daily versus roughly 140 before the war .

Ongoing Risks: Naval Mines

The biggest physical obstacle is the mine threat.

• Approximately 80 naval mines remain in the central area of the Strait of Hormuz and must be cleared before regular shipping can recommence, according to the independent organization representing tanker owners .
• Until the lanes are swept and declared safe by shipping companies and their insurers, most commercial operators will not risk transit .
• A Joint Maritime Information Center (JMIC) advisory warned mariners: "Do not attempt to cross until explicit direction is given" .

Stranded Ships

• As of June 18, more than 550 ships remained stranded on either side of the strait waiting to transit .
• A broader estimate from earlier in June (before the ceasefire collapsed and was reinstated) put the figure at over 800 vessels .
• Many of these ships are laden oil tankers, LNG carriers, and container vessels that have been trapped for weeks or months, with some crews facing extended deployments and logistical strain .

Expert Timelines for Full Shipping Restoration

Bottom line from available evidence: Even before the Switzerland talks collapsed, experts saw a multi-week to multi-month recovery path due to mines, the vessel backlog, damaged port infrastructure, and the need for insurers to re-certify the route as safe . The cancellation of the nuclear talks has now added a severe political uncertainty premium that will likely delay any large-scale resumption until the diplomatic track is revived.