By Tim Lister, Zachary Cohen, Hira Humayun, Lex Harvey, CNN

(CNN) — At least seven oil tankers have been struck in and beyond the Persian Gulf since Tuesday evening local time, as the United States and Iran step up tanker attacks in what could mark a dangerous new phase in the war.

The escalation led global oil prices to rise briefly above $100 per barrel for the first time since July. Brent crude, the global oil benchmark, rose 2.3% before falling back slightly.

Late Tuesday, the US military struck five Iranian tankers, sinking one, after Iran fired ballistic missiles at a US Navy warship.

Four crude oil carriers in the Gulf of Oman and one near Kharg Island – a hub for Iranian oil exports in the Persian Gulf – were struck, US Central Command (CENTCOM) said.

One of the ships, identified as the M/T Riesco, is seen on fire and sinking in the Gulf of Oman in a video posted to X by the military. US forces instructed the crews of the vessels they targeted to abandon ship prior to striking, CENTCOM said.

Iran retaliated by firing a barrage of missiles toward regional US ally Jordan, saying it was targeting Muwaffaq Salti Air Base, a key facility used by US forces.

The barrage was ineffective in face of integrated air and missile defenses, a US official told CNN.

The Jordanian army said its air defenses dealt with 20 ballistic missiles, 18 of them successfully destroyed, with two falling in unpopulated areas.

On Wednesday, two tankers in the Gulf were struck by drones. One was off Dubai’s coast, the other in Iraqi waters.

A seafarer was killed in an incident involving the Gibraltar-flagged oil products tanker Hercules Star while at anchorage ⁠off Dubai, the vessel’s charterer, Peninsula, said on ⁠Wednesday. It gave no cause of death.

The United Kingdom Maritime Trade ⁠Operations (UKMTO) center said earlier that a vessel in the same area was seen listing, indicating that it could be taking on water after an attack from an “unknown projectile.

Further north, a Panama-flagged tanker was struck by an unknown source in Iraqi waters, causing damage to the vessel’s hull, according to the Iraqi Ministry of Transport.

The incident caused no casualties or injuries among the crew, the ministry said.

There’s been no claim of responsibility for the attacks on the two tankers.

But Iran’s Islamic Revolutionary Guard Corps (IRGC) had warned “all crews aboard oil tankers in the vicinity of ports in Kuwait and Bahrain – which host these (US) terrorists and are partners in their hostile actions – to immediately leave their vessels, whether they are at anchor or docked at the ports, as the vessels will be targeted.”

The US strikes were in response to Iranian attempts to attack a US Navy ship over the past two days. The US ship evaded the missiles and was continuing to patrol regional waters, CENTCOM said, adding that “no American personnel were harmed.”

The exchange of strikes comes as the US has focused its strategy on ramping up economic pressure on the Tehran regime, while conducting escort operations for commercial vessels through the Strait of Hormuz and maintaining its naval blockade on Iranian ports.

Over the weekend US forces hit three Iranian crude oil carriers in response to an Iranian attempt to attack a US aircraft carrier and guided-missile destroyer.

‘Pattern of gradual escalation’

Iran’s repeated attempts to attack US warships and the increased “quality and quantity” of the missiles it fired at US targets in the region showed “a pattern of gradual escalation,” said Hamidreza Azizi, senior Iran analyst at the International Crisis Group think tank, on X.

US Secretary of State Marco Rubio, during his trip to Colombia, warned Tehran that the US would respond every time Iran targeted its naval ships.

“Iran continues to try to hit US naval ships and for every time they do that, or try to do that, they’re going to lose tankers,” he told reporters in the city of Barranquilla.

Iran has also announced that it will expand its maritime restriction zone in the Persian Gulf region.

A spokesman for the Islamic Revolutionary Guard Corps (IRGC), General Hossein Mohebbi, said the expanded zone would start “approximately from the direction of Chabahar,” an Iranian port city on the Gulf of Oman, and would include “another part of the Arabian Sea along the route leading to the Strait of Hormuz.”

Exact coordinates would be announced later, he said.

Tehran has sought to maintain leverage over transits through the strait as a way to keep oil prices high and put pressure on the Trump administration.

Gasoline prices in the US climbed to a fresh three-month high above $4.15 a gallon on Tuesday.

On Wednesday Trump said he expects Iran will abandon its war effort after the US midterm elections — and that American gas prices are unlikely to come down before then.

This story has been updated with additional information.