According to data from maritime intelligence firm Windward, maritime traffic through the strategically crucial Strait of Hormuz came to a complete standstill over the past weekend.
The data indicates that a recent, brief recovery in tanker traffic observed last week through this vital global oil transit chokepoint has now been disrupted.
Iran announced the blockade of the Strait on Saturday, citing ongoing deadly Israeli strikes in southern Lebanon as a violation of the ceasefire agreement.
On June 21, 2026, in Muscat, Oman, multiple tankers and cargo ships were anchored off the coast of Port Sultan Qaboos. The Strait of Hormuz has been effectively under blockade since the outbreak of war between the U.S. and Iran in late February. On Sunday, U.S. Vice President Vance arrived in Switzerland for high-level talks with an Iranian delegation aimed at finalizing the terms of a ceasefire agreement.
Maritime intelligence firm Windward stated that following Iran's announcement of the renewed blockade of this key global oil shipping route, maritime traffic through the Strait of Hormuz completely stalled over the weekend.
However, industry tracking data shows that tankers flying the Iranian flag continued to transit the narrow waterway normally. Approximately 20% of global oil trade passes through the Strait of Hormuz.
After the U.S. and Iran signed a 14-point memorandum of understanding last week, tanker traffic through the Strait saw a brief uptick, but the latest monitoring data indicates this recovery has been interrupted.
Windward's analysis report shows that on Sunday, only 12 vessels transited the Strait of Hormuz, compared to 21 vessels the previous day. Of the 8 inbound vessels, 5 were in "dark" status, meaning they had turned off their Automatic Identification System (AIS) transponders, concealing their location, flag, and destination.
Windward stated on social media on Sunday: "Current traffic is highly characterized by vessels going dark, under international sanctions, and linked to Iran. The situation is more akin to the low levels seen at the end of a blockade, far from a fully open waterway."
Data from shipping intelligence firm Kpler last week showed that at least 20 tankers transited the Strait of Hormuz on Thursday, the highest volume since June 2, but still far below pre-war levels—during peacetime, hundreds of vessels (including dozens of tankers) pass through daily.
Independent monitoring data from maritime authority Lloyd's List on Monday indicated that despite Iran's announcement of a renewed blockade, commercial vessels continued to transit the Strait of Hormuz normally over the weekend.
Iran announced the blockade of this strategic waterway on Saturday, citing Israel's ongoing deadly military strikes in southern Lebanon as a violation of the ceasefire terms.
The U.S. military denied this, stating the waterway remains open and that "control of the Strait of Hormuz does not belong to Iran."
According to Lloyd's List, as of Saturday evening, at least 15 Iranian-flagged Suezmax tankers and Very Large Crude Carriers (VLCCs) were sailing from the Gulf of Oman into open waters with their AIS signals active.
Progress of U.S.-Iran Negotiations in Switzerland
On Sunday, the U.S. and Iran began talks at a mountain resort in Switzerland, building on the memorandum of understanding signed by both sides on Wednesday.
It is reported that the negotiations have made incremental progress towards reaching a final ceasefire agreement within 60 days, with both sides agreeing to establish a dedicated committee and mechanism to end the armed conflict in Lebanon.
A Pakistani senior official and an Iranian official participating in the Bürgenstock talks informed this outlet that the negotiations continued into the early hours, with an overall constructive but tense atmosphere.
According to the previously signed memorandum of understanding, both sides committed to keeping the Strait of Hormuz open for free navigation for at least 60 days and to a complete cessation of all hostilities, including the fighting in Lebanon between Israel and the Iran-backed Hezbollah.
Iranian Foreign Minister Abbas Araghchi stated that Iran has secured several concessions: exemptions from sanctions for oil and petrochemical product exports, the lifting of the blockade on its ports, the unfreezing of some overseas assets, and permission to initiate regional reconstruction and development plans.
Prior to the start of the Swiss talks, former President Trump threatened a new strike against Iran. He stated on social media on Sunday: "Iran must immediately stop its heavily funded proxies in Lebanon from causing trouble. If not, we will hit Iran again, harder than last week!"
On June 21, 2026, in the southern Iranian port city of Bandar Abbas, several large commercial vessels and smaller boats were navigating the port waters. Following the U.S. easing of blockade restrictions on the Strait of Hormuz, Iranian commercial shipping activity has resumed, with a notable increase in frequency along this key maritime route.
The U.S. delegation is led by Vice President Vance, who remains optimistic about the prospects of the Swiss talks despite Iran's renewed threats to blockade the Strait.
Regarding the armed conflict in Lebanon, Vance downplayed its negative impact, stating that local ceasefire negotiations have made substantial progress: "Geopolitical negotiations are always accompanied by twists and chaos, and this one is no exception."
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