(Bloomberg) -- The Iranian oil tanker that the U.S. sought to seize in Gibraltar was about halfway into the Mediterranean Sea on the way to Turkey on Sunday amid mounting speculation over where the roughly 2 million-barrel cargo of crude on board will end up.

The Adrian Darya 1 signaled Turkey’s port of Mersin as its destination on Saturday morning local time, switching from the previous target of Kalamata in Greece, according to Bloomberg tanker-tracking data. Greek officials including the prime minister said the ship would be unwelcome in the country after the U.S. threatened sanctions against anyone aiding the tanker.

Iran’s tanker fleet is under intense scrutiny as the U.S. seeks to cut off the Islamic republic’s ability to sell crude, normally the country’s main export earner. Iran’s oil sales have tumbled under U.S. sanctions threatening to punish most interactions with the Iranian government over its nuclear program. Iran and other signatories to the 2015 nuclear agreement with the Islamic Republic oppose the U.S. measures.

By Sunday morning, the Adrian Darya 1, which had changed names from Grace 1, had passed below the Italian island of Sicily and was set to arrive at Mersin, located just 150 kilometers from the border with Syria, at noon on August 31, according to tanker-tracking data. The vessel resumed the journey last week after being released by authorities in Gibraltar. British authorities had blocked the vessel, alleging the crude on board was headed to Syria.

If Turkey were to accept the ship, that would risk further fueling tensions with the U.S., at a time when relations have been strained over Turkey’s decision to buy a missile defense system from Russia. Turkey’s government declined to comment on whether they would allow the ship to dock at Mersin.

A U.S. attempt to seize the tanker before leaving Gibraltar was denied by a court in Gibraltar. A court in the territory refused the petition from the American government since, while European Union rules prohibit dealing with sanctioned entities in Syria, they are less comprehensive than U.S. sanctions law with regards to Iranian oil sales.

The Trump Administration has since sought to block the tanker’s voyage by threatening sanctions to stop the Adrian Darya 1 from being able to call in any port or offload any oil. The vessel may seek to transfer the crude to smaller ships for delivery to Turkey or Syria and could “go dark,” turning off its satellite transponder to mask the location of any unloading.

To contact the reporter on this story: Anthony DiPaola in Dubai at adipaola@bloomberg.net

To contact the editors responsible for this story: Nayla Razzouk at nrazzouk2@bloomberg.net, Alaa Shahine

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