Gibraltar Chief Minister Fabian Picardo said earlier that his government "had reasons to believe" that the tanker was headed to the Banyas Refinery, which belongs to an entity that is subject to the EU sanctions against Syria.
US National Security Advisor John Bolton called Thursday the seizure of the oil tanker "excellent news".
Excellent news: UK has detained the supertanker Grace I laden with Iranian oil bound for Syria in violation of EU sanctions. America & our allies will continue to prevent regimes in Tehran & Damascus from profiting off this illicit trade.— John Bolton (@AmbJohnBolton) 4 июля 2019 г.
Following the incident, the Foreign Ministry of Iran summoned the UK Ambassador in Tehran Rob Macaire to express its decisive protest over the seizure of the vessel.
The Panama-flagged supertanker Grace 1 was reportedly carrying 2 million barrels of crude oil.
Relations between Washington and Tehran deteriorated after the United States exited the nuclear deal last year and re-imposed sanctions on Iran. In May, on the one year anniversary of Trump's pullout from the nuclear agreement, Iran announced it had partially discontinued its commitments under the accord and gave the other signatories 60 days to protect Tehran’s interests.
Earlier in June, Trump said he was willing to begin negotiations with Iran with no preconditions and would consider reaching a bilateral or multilateral agreement. Iran’s Ambassador to the United Nations Majid Takht Ravanchi said last Thursday that the United States is not ready for pursuing dialogue with Iran because the sanctions against the Islamic Republic remain in place.
Meanwhile, tensions in the Middle East have recently escalated in the wake of attacks on oil tankers between the Persian Gulf and the Gulf of Oman. The United States blamed the attacks on Iran and boosted its military presence in the region, while Tehran dismissed claims it had any role in the incident.
The United States has also vowed to drive Iran's oil exports down to zero and demanded that other countries stop any such oil purchases from the Islamic Republic.