After weekend peace talks between U.S. and Iranian negotiators in Islamabad concluded without agreement, President Donald Trump announced that the U.S. Navy would "begin the process of blocking all vessels attempting to enter or exit the Strait of Hormuz." The U.S. Central Command stated that unauthorized ships entering or leaving the blocked area would face "interception, diversion, and seizure," noting that U.S. forces would not impede the freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports. Iran’s Revolutionary Guard responded with a warning that military vessels approaching the strait would be considered a violation of the ceasefire and dealt with harshly and decisively. A blockade of Iranian oil exports would disrupt a significant source of global market supply, as Iran exported 1.84 million barrels of crude oil per day in March and, so far in April, 1.71 million barrels per day, compared to an average of 1.68 million barrels in 2025, according to Kpler data. Simultaneously, a sharp increase in Iranian production before the war began on February 28 led to near-record volumes of Iranian oil being loaded onto ships. At the beginning of the month, tankers held over 180 million barrels in transit or floating storage, with about 100 million barrels located in waters near Malaysia, Indonesia, and China. Maritime traffic through the Strait of Hormuz, heavily restricted by an Iranian blockade since the start of the war, remained largely halted despite a two-week ceasefire between Washington and Tehran announced on April 7. On Tuesday, a Chinese tanker carrying methanol loaded in Hamriyah, United Arab Emirates, passed through the strait in what appears to be the first tanker transit since the U.S. blockade began, with two other ships also crossing. On Sunday, before the blockade started, two Pakistan-flagged tankers, Shalamar and Khairpur, entered the Gulf to load cargo from the United Arab Emirates and Kuwait, while a third vessel, the Liberia-flagged very large crude carrier (VLCC) Mombasa B, also transited the strait and ballasted in the Gulf. The Malta-flagged VLCC Agios Fanourios I, which attempted to pass through the strait on Sunday to load Iraqi oil destined for Vietnam, turned around and anchored near the Gulf of Oman. According to Kpler data, around 187 loaded tankers carrying 172 million barrels of crude oil and refined products were in the Gulf on April 7. Before the war, most Iranian oil exports were delivered to China, the world’s largest crude importer, and last month the U.S. announced a sanctions waiver enabling other buyers, including India, to import Iranian oil. India was set to receive its first shipment of crude oil from Iran in seven years this week, according to ship-tracking data from LSEG and Kpler. Before the conflict erupted, about 20% of global oil and natural gas exports passed through the Strait of Hormuz, with most cargo destined for Asia, the largest importing region.