The U.S. military has released additional photos that it claims bolster allegations that Iran was responsible for attacks last week on two oil tankers in the Gulf of Oman.
The Pentagon on June 17 released images, many taken from a U.S. Navy helicopter and purporting to show Iranian forces removing an unexploded mine from the hull of the Japanese-owned Kokula Courageous oil tanker.
Washington has said the photos appeared to show an attempt to remove evidence from the scene of the incident.
The same day, the Pentagon announced it would send some 1,000 additional troops to the Middle East because of the tanker attack.
Acting Defense Secretary Patrick Shanahan said the troops were "for defensive purposes to address air, naval, and ground-based threats in the Middle East."
He added that the United States "will continue to monitor the situation diligently and make adjustments to force levels as necessary given intelligence reporting and credible threats."
Earlier, the Pentagon released video footage of the purported mine removal.
Iran has denied any involvement in the attack.
The United States has also accused Iran's Islamic Revolutionary Guards Corps (IRGC) of attempting to shoot down a U.S. drone that was monitoring the tankers when the attack occurred.
Relations between the United States and Iran have been tense since U.S. President Donald Trump in 2018 unilaterally withdrew from an international agreement that restricted Iran's nuclear program in exchange for sanctions relief.
On June 17, Iran's nuclear-energy agency said Tehra would surpass a uranium-stockpile limit set by the 2015 nuclear deal within the next 10 days. Agency head Behrouz Kamalvandi added that Iran will continue to allow the UN's International Atomic Energy Agency (IAEA) to monitor its nuclear facilities for now.
Trump has said the 2015 deal was "fatally flawed" because it did not address Iran's ballistic missile program or Tehran's purported support for terrorist organizations.
In April, Trump designated the IRGC as a foreign terrorist organization, the first time the United States has labelled another nation's military as a terrorist group.