dubai, April 25 -- Iran is continuing to load millions of barrels of oil onto supertankers, an activity that will only become increasingly difficult if the US keeps up a blockade on Tehran's shipping. Images from the European Union's Sentinel 1 satellite, captured on Monday, show one very large crude carrier (VLCC) that's capable of hauling about 2 million barrels of oil, moored at the jetty on Kharg Island. An earlier image from Saturday showed no ships moored at Kharg. With no evidence of large volumes of oil circumventing the US blockade, the loaded crude is likely filling up tankers Iran has available in the region. Monday's image shows 13 ships, most of them VLCCs, anchored to the east of the island. An image from the day before the blockade started on April 13 shows about half that number. The US said its maritime barrier in the Sea of Oman has stopped almost three dozen Iranian vessels from passing, keeping crude from the Islamic Republic reaching customers. As President Donald Trump's administration tries to slash oil revenue that's crucial for Iran, market watchers are looking for evidence on how long Tehran can maintain production. Iran has attempted several times to break the American blockade. The US Navy says it intercepted at least two supertankers in the Gulf of Oman and the Arabian Sea this week. It has forced those and other ships to turn around and head to an Iranian port, with a build-up of oil tankers and other vessels seen off the Iranian port of Chabahar, close to the border with Pakistan. Iran has been the only major oil exporter out of the Persian Gulf since the war in the Middle East started in late February, after Tehran effectively closed off the Strait of Hormuz to other maritime traffic. Lower shipments will also hit Tehran's oil revenue, the backbone of the country's finances. The US actions are likely to eventually force Iran to curtail production if tankers are unable to transit. The move "would constrain volumes mechanically, not just financially, leaving far less room for workaround trade, and, over time, forcing Iran to curtail production," JPMorgan Chase & Co. analysts including Natasha Kaneva wrote in a note. But the process won't be quick. Iran has 90 million barrels of available storage and could maintain oil production at current levels of about 3.5 million barrels a day for another two months, even if the US blockade succeeds in halting the country's exports, FGE NexantECA said in a note. A US-sanctioned supertanker laden with Iranian oil appeared to halt its transit through the Strait of Hormuz on Friday, with traffic through the waterway otherwise at a virtual standstill....