WASHINGTON (AP) — The U.S. military has stopped another merchant vessel trying to break through the American blockade of Iranian ports, a U.S. official with knowledge of the situation told The Associated Press on Saturday.

The Gambia-flagged bulk carrier Lian Star ignored multiple warnings from U.S. forces overnight as it tried to enter an Iranian port, the official, who spoke on condition of anonymity to discuss military operations, said. The ship was disabled by U.S. aircraft in the Gulf of Oman and remains adrift there, the official said, adding that U.S. forces have not boarded it.

With the latest action, U.S. military has stopped six ships trying to breach the blockade. One was allowed to proceed.

The U.S. launched the blockade on April 17 in response to Iran effectively closing the strait after the war began with U.S. and Israeli strikes on Feb. 28. A fragile ceasefire has held since April 7. Now the region and wider world await word on whether a deal is being reached to extend it by 60 days while new talks would be held on Iran’s disputed nuclear program.

Events in the Strait of Hormuz between Iran and Oman have shaken the global economy, with shipments of significant amounts of oil, natural gas and related supplies like fertilizer largely stranded, increasing the strain on consumers and food producers.

The U.S. blockade seeks to limit Iran’s own shipments and further weaken its access to cash, creating more pain for its long-weakened economy.

U.S. President Donald Trump met with advisers on Friday but has yet to decide on whether to move ahead with a deal to extend the ceasefire and reopen the strait. Iran has said the deal had not been finalized.

Commercial traffic has quietly continued to flow through the strait, despite Iran’s assertions that it must approve any transits, though at a much lower volume than before the conflict.

“Any violation of these regulations will place the security of their passage at serious risk,” Iran’s joint military command said Saturday in a statement carried by state TV, warning that any military vessels trying to interfere with that would be targeted.

Iran has even charged tolls for transit as high as $2 million, which experts have called a violation of a principle of international maritime trade: freedom of peaceful navigation.

Qatar’s deputy prime minister, Sheikh Saoud bin Abdulrahman bin Hassan bin Ali Al Thani, on Saturday said the Gulf nation opposes charging fees to transit, “but for certain times when they say they are going to use it for mine clearing or some usage of the fees for a temporary time, this is something that is negotiable, and it could be something that will help the transit of the Strait of Hormuz to be back to normal stage.”

The U.S. official previously told the AP that the U.S. has not found or destroyed any mines in the strait.