Bahrain and Kuwait secretly sent fighter jets into Iran earlier this month to attack drone and missile facilities, marking their first known direct military retaliation against Tehran after weeks of Iranian attacks, according to people familiar with the operation.

The strikes targeted drone and missile storage depots and other military sites, The Wall Street Journal reported Friday, citing unidentified people familiar with the matter.

The United Arab Emirates, which carried out several attacks against Iran earlier in the conflict, provided intelligence on the targets and defensive air cover for the operation, the report said.

Neither Bahrain nor Kuwait has publicly acknowledged the strikes, and government spokespeople for the two Gulf countries did not respond to requests for comment.

The operation would represent a significant expansion of direct Gulf Arab involvement in the war and a departure from the cautious policies that regional governments have pursued toward Iran.

Bahrain and Kuwait have relatively small air forces equipped largely with U.S. and European aircraft, but officials determined that they could not allow Tehran to continue attacking their countries without responding, according to the people familiar with the matter.

Iran has concentrated attacks on Bahrain and Kuwait in recent weeks because both countries host major U.S. military installations.

Bahrain is home to the U.S. Navy's 5th Fleet, while Kuwait hosts thousands of American service members at several facilities.

Kuwait's Foreign Ministry said Sunday that Iran had attacked a power-generation and water-desalination facility, describing the strike against vital civilian infrastructure as a dangerous escalation and a violation of international law.

Kuwait and Bahrain have repeatedly activated their air defenses to intercept Iranian missiles and drones during the widening conflict, although officials have not announced large numbers of casualties from the attacks.

The UAE's Foreign Ministry has called for lower regional tensions and the full reopening of the Strait of Hormuz while condemning attacks on Kuwait and Bahrain.

It said it "stands in full solidarity with these states and reaffirms its support for all measures aimed at safeguarding their security and stability."

The war, which began with U.S. and Israeli attacks on Iran on Feb. 28, has entered its fifth month, disrupting Gulf oil exports through the Strait of Hormuz, damaging tourism and investment, and spreading to the Red Sea.

Iran-backed Houthi forces in Yemen have threatened Saudi-linked commercial shipping near the Bab el-Mandeb Strait, raising concerns about another critical route for global energy supplies.

The United States widened its campaign Friday with strikes across Iran after Tehran attacked American bases in Bahrain, Kuwait, and elsewhere.

"The war continuing in the manner that it is playing out right now is their worst-case scenario," said Dina Esfandiary, a Middle East analyst at Bloomberg Economics.

"That is because it does not give them the opportunity to rebuild and maintain their image as a haven for stability in an unstable region. It affects their very models."

Umer Karim, a researcher at the University of Birmingham, said, "I think Gulf countries are beginning to realize that this war will continue for some time now. This eventually means that they would have to confront Iran openly."