I mean I feel like most people who are following along with this could easily see this coming from a mile away. Even with the UAE hosting U.S. military forces, the much bigger prize for Iran isn't in the UAE, it's in Saudi Arabia. Since this is coming out it will be interesting to see how the rest of the Gulf States react. The UAE has been on the outs and butting heads with Saudi Arabia for the last couple of years in their proxy wars so is this going to be something that mends fences and unites them?

DUBAI—The United Arab Emirates has carried out military strikes on Iran, people familiar with the matter said, casting the Gulf monarchy as an active combatant in a war in which it has been Iran’s biggest target.

Its military is well-equipped with Western-made jet fighters and surveillance networks. And the attacks suggest the country is now more willing to use them to protect its economic power and growing influence across the Middle East.

The strikes, which the U.A.E. hasn’t publicly acknowledged, have included an attack on a refinery on Iran’s Lavan Island in the Persian Gulf, the people familiar with the matter said. That attack took place in early April around the time President Trump was announcing a cease-fire in the war after a five-week air campaign and sparked a large fire and knocked much of its capacity off line for months.

Iran said at the time that the refinery had been struck in an enemy attack and launched a barrage of missile and drone strikes against the U.A.E. and Kuwait in response.

The U.S. wasn’t upset by the attack, as the cease-fire hadn’t yet settled into place, and it has quietly welcomed the participation of the U.A.E. and any other Gulf states that want to join in the fight, one of the people said.

The U.A.E.’s Ministry of Foreign Affairs declined to comment on the strikes but pointed to previous statements in which it asserted its right to respond—including militarily—to hostile acts.

The Pentagon declined to comment. The White House didn’t address questions about the U.A.E.’s involvement during the war but said that President Trump has every option at his disposal, and that the U.S. has maximum leverage over the Iranian regime.

“It’s significant to have a Gulf Arab country as a warring party that struck Iran directly,” said Dina Esfandiary, Middle East analyst and author of a book on the rise of the U.A.E. “Tehran will now aim to further drive a wedge between the U.A.E. and other Gulf Arabs who are trying to mediate an end to the war.”

Gulf countries said ahead of the war they wouldn’t let their airspace or bases be used for attacks. But once the war started, Iran responded by launching missile and drone attacks against Gulf population centers, energy infrastructure and airports in an effort to raise the economic and political costs and make it harder for the U.S. and Israel to continue the attack.

Iran focused much of its fire on the U.A.E., targeting it with more than 2,800 missiles and drones—far more than any other country, including Israel.

The attacks have hammered the U.A.E.’s air traffic, tourism and property market, and have led to a wave of furloughs and layoffs. They also have prompted a fundamental shift in the country’s strategic outlook to one that now sees Iran as a rogue actor bent on undermining the country’s economic and social model based on expatriate talent and a reputation for safety and stability, Gulf officials have said.

The U.A.E. has since emerged as the most openly confrontational country in the Gulf and has maintained strong military cooperation with the U.S. throughout the war, according to people familiar with the matter.

“The Emiratis made it clear early on that they didn’t want this war, but it’s also clear that since the first Iranian strikes on the U.A.E. took place, Abu Dhabi’s been quite transparent that they see the regional picture as having changed dramatically,” said H.A. Hellyer, senior fellow at the Royal United Services Institute for Defense and Security Studies in London. “Abu Dhabi hasn’t confirmed what they have targeted, or even if they have targeted, but from the early days of the war it seemed only a matter of time before we saw increased kinetic involvement of different Gulf states in the war.”

Speculation about the U.A.E.’s involvement in the war has swirled since mid-March, when a jet fighter that didn’t appear to belong to Israel or the U.S. was filmed over Iran.

Researchers who track publicly available images and other information have pointed to photos purporting to show French Mirage fighters and Chinese Wing Loong drones—both used by the U.A.E.—in action in Iran.

Militarily, the U.A.E. is dwarfed by the U.S. But it has a highly trained and capable air force with Mirages and a fleet of advanced F-16 jet fighters supported by refueling planes, command and control aircraft and surveillance drones.

Those capabilities give it unusually sophisticated air power for the region, according to retired U.S. Air Force Lt. Gen. Dave Deptula, who planned the air campaign for Desert Storm.

“They are very strong in terms of precision strike, air defense, airborne surveillance, refueling, and logistics,” Deptula said. “If you have that capable of an air force, why would you sit back and absorb attacks from Iran without responding?”

Tehran’s strategy of pulling the Gulf into the war has exacerbated political divisions among its Arab monarchies and sent them scrambling for new arrangements that might guarantee their security.

While all Gulf states are wrestling with growing security risks and the reliability of their American protector, the Emirates is doubling down on its relationship with the U.S., Anwar Gargash, diplomatic adviser to the United Arab Emirates president, told a group of reporters in April.

In addition to the strikes, the U.A.E. backed drafts of a resolution at the United Nations that authorized the use of force if necessary to break Iran’s chokehold on the strategic Strait of Hormuz waterway.

The U.A.E. also acted against Iran’s financial interests, closing schools and clubs in Dubai that were linked to Tehran and denying visas and transit rights to Iranian citizens. The moves crimped the economic lifeline the Emirates have long provided to Iran amid heavy sanctions by the West.

Iran has responded by repeatedly accusing the U.A.E. of joining the U.S. and Israeli campaign.

After the U.S. and Israel wiped out Tehran’s air-defense capabilities, the risk of flying combat missions over the country dropped sharply, said retired Col. John “JV” Venable, who commanded operations at the Al Udeid air base in Qatar during his time in the U.S. Air Force.

“If you’re an ally and you want to be engaged, it’s a really good time to do that, because the threat is really low,” Venable said. “At medium to high altitude, aircraft are going to be able to do what they want, and there’s nothing the Iranians can do about it.”