Oil prices climbed Sunday after Iran once again blocked the passage of most ships through the Strait of Hormuz, a key waterway for one-fifth of the world’s crude.

Brent crude, the international benchmark, was up about 7% to $96.88, after settling on Friday at its lowest level since March 10 on news Iran would re-open the strait. US crude was up 7% to $90.33.

But it remained unclear how open the strait truly was and which ships would be able to transit when. And on Saturday, Iran said it was closing the Strait of Hormuz again, blaming the United States for “breaches of trust.”

After announcing the closure on Saturday, Iranian gunboats fired on tankers attempting to pass through the strait, which President Donald Trump on Sunday called a “violation” of the ceasefire, adding that “our BLOCKADE has already closed (the Strait of Hormuz).”

The US military on Sunday fired “several rounds” towards an Iranian-flagged ship attempting to violate the US naval blockade, raising fears that the war will escalate in the coming weeks. The US ultimately seized the Iranian-flagged “Touska,” according to US Central Command.

Iran’s military warned that it would soon respond and “retaliate against this U.S. armed piracy,” according to state media.

No tankers crossed the strait Sunday, according to tracking data.

Trump said a US delegation is headed to Pakistan for peace talks with Iran. Trump has warned he will not extend the ceasefire if an agreement isn’t reached by Wednesday. Iranian negotiators will arrive in Pakistan on Tuesday, sources told CNN, but Tehran has not publicly confirmed attendance.

Iran and the US are also “far from a final agreement,” Mohammad Bagher Ghalibaf, Iran’s parliamentary speaker and top negotiator, told state television Sunday.

US gas prices, which reached a national average of $4.05 a gallon on Sunday, may not return to under $3 a gallon until “next year,” Energy Secretary Chris Wright told CNN on Sunday, while not ruling out the possibility that the benchmark is reached “later this year.”

Meanwhile, Dow futures were down 0.91%, or 451 points. S&P 500 and Nasdaq futures were both down roughly 0.8%. (CNN)

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