Iran's army warned on Sunday that countries complying with U.S. sanctions against the Islamic republic would face difficulties crossing the Strait of Hormuz.

An unknown projectile struck a ship off the coast of Qatar early Sunday morning, a UK maritime agency reported, after Iran's Islamic Revolutionary Guards threatened to target U.S. vessels in the region.

U.S. President Donald Trump said Friday that he was expecting Iran's response to Washington's latest proposal on a deal to ending the Middle East war by "tonight."

A U.S. fighter jet disabled two Iranian-flagged tankers to enforce a port blockade on Friday, prompting retaliatory attacks and rattling a shaky truce as Tehran weighed Washington's latest proposal to end the Middle East war.

U.S. Secretary of State Marco Rubio on Friday slammed Iranian efforts to control the Strait of Hormuz, following a report that Tehran has created an authority to approve transit through the vital waterway.

"Iran now claims that they own, that they have a right to control, an international waterway... That's an unacceptable thing that they're trying to normalise," Rubio told reporters during a visit to Rome.

The United Arab Emirates said it responded to another Iranian missile barrage on Friday, hours after the U.S. said it traded fire with Iranian forces in the Strait of Hormuz, in the latest blows to a shaky month-old ceasefire.

The UAE’s Defense Ministry said three people were wounded after air defenses engaged two ballistic missiles and three drones launched by Iran. It was not clear if all were successfully intercepted. Authorities told people to stay away from any fallen debris.

The U.S. military said it carried out strikes on Iranian military targets in response, although Tehran charged that it was Washington that had initiated the exchange of fire.

The latest violence threatens to unravel a fragile truce in effect since April 8 that brought an end to weeks of U.S.-Israeli attacks on the Islamic republic, which has retaliated with strikes across the Middle East and by blocking the strait, a vital route for oil and gas shipments.

Iran said it was reviewing the latest American proposals on ending the war, as U.S. President Donald Trump threatened the country with a new wave of bombing unless a deal is reached that includes reopening the crucial Strait of Hormuz to international shipping.

Hope that the two-month conflict could soon end buoyed international markets on Thursday, even as the U.S. military fired on an Iranian oil tanker attempting to breach an American blockade of Iran's ports hours earlier. The developments followed days of mixed messaging from the Trump administration over its strategy to end the war.

France's aircraft carrier strike group is moving south of the Suez Canal and into the Red Sea in preparation for a potential French-British mission in the Strait of Hormuz, French President Emmanuel Macron said Wednesday.

The deployment puts Europe's most powerful warship closer to the strait whose effective closure has come to epitomize the war in Iran, stranding hundreds of ships and triggering what the International Energy Agency calls the largest supply disruption in the history of the global oil market.

Iran denied on Thursday attacking a South Korean cargo ship in the Strait of Hormuz this week, as U.S. President Donald Trump said a deal to end the war was "very possible" but warned Washington would resume bombing if talks failed.

Tehran's embassy in Seoul said it "firmly rejects and categorically denies" allegations that its armed forces were behind a blast aboard the Panama-flagged HMM Namu, which caught fire on Monday while transiting the strategic waterway with 24 crew members on board.