Dubai. US President Donald Trump on Tuesday backtracked on plans to charge ships for using the Strait of Hormuz, saying Gulf countries would instead invest in the United States. Another wave of US strikes on Iran, and Iranian attacks on shipping and American allies, left an interim peace deal in tatters.

That agreement was supposed to reopen a waterway that is key to world energy supplies and give negotiators time to hammer out a permanent end to the war. Instead, fighting has once again engulfed the region, threatened the global economy and brought warnings to commercial airlines.

The focus of the conflict now is the strait, through which a fifth of all traded crude oil and natural gas passed in peacetime. Iran effectively shut the passage during the war by attacking and threatening ships -- a tactic that proved its greatest strategic advantage. It sent the price of oil, fertilizer, and other goods soaring at a time when world leaders were already struggling to address rising costs.

Iran has more recently attacked ships moving through the strait on a route overseen by the U.S. military that is outside Tehran’s control, setting off tit-for-tat strikes. The US has threatened to reopen the strait by force — but experts say that would require a much bigger armada if not tens of thousands of ground troops.

On Monday, Trump said the US would reimpose a blockade on Iranian ports and begin charging ships fees equivalent to 20% of their cargo to defray the costs of securing the strait. He backed off on the fees a day later, while the blockade is set to come back into force in the coming hours.

“Based on highly productive conversations with Middle East leadership, I have decided to replace the 20% United States Reimbursement Fee with Trade and Investment Deals that the various Gulf States will be making into the United States,” Trump said on social media.

The president said the investments “will be MASSIVE,” though it’s unclear if these would be new commitments relative to what Trump announced after a visit last year to the Middle East.

Strikes and Counterstrikes Resume Across the Mideast
The US military’s Central Command said it struck several areas in Iran, targeting “coastal defense systems, missile and drone sites and maritime capabilities.” Iran acknowledged the strikes but provided no immediate casualty or damage assessments.

“These strikes will continue imposing a heavy cost on Iranian forces and degrade their ability to attack innocent civilians and commercial shipping in the Strait of Hormuz,” the US military said.

Iran responded with attacks targeting Bahrain, Jordan, and three tankers that traveled through the strait. Kuwait's military said it was responding to an aerial attack without providing further details.

Two of the ships were associated with the United Arab Emirates and were set ablaze for a time. The International Maritime Organization said the attack on the tankers Mombasa and Al Bahiyah killed two mariners and wounded 14 others. The Emirates threatened to retaliate.

Dutch shipping firm Stolt Tankers said that one of its ships came under attack. The attack on the Stolt Magnesium off Oman sparked a fire in the engine room, but the company said all the mariners were safe.

Iran’s paramilitary Revolutionary Guard said the Mombasa and Al Bahiyah “ignored repeated warnings.” Iran has targeted ships that use a route through the strait that passes near Oman outside of its territorial waters.

Hours after the U.S. said it ended its campaign of strikes, the Iranian city of Bushehr on the Persian Gulf was hit in at least four locations, the state-run IRNA news agency reported. The attacks again raised the possibility that Gulf Arab states were retaliating against Iran without discussing it in public.

The European Union Aviation Safety Agency warned airlines against operating in the airspace of Bahrain, Kuwait, Qatar, and the United Arab Emirates, as well as over the Gulf of Oman.

It said in a bulletin that “unpredictable military developments, combined with the possible use of missiles, drones, combat aircraft and air-defense systems, create a high risk to civil flights.”