A spokesman for the Saudi-led coalition targeting rebels in Yemen with airstrikes said Tuesday that the so-called "Decisive Storm" campaign is over, but that allies will launch a new phase aimed at stopping the rebels.

Speaking at a news conference in Riyadh on Tuesday, Brig. Gen. Ahmed Asiri said the objectives of the campaign have been met and that it would cease at midnight.

He said the rebels no longer pose a danger to civilians and that the new phase, called "Renewal of Hope" would focus on rebuilding the country while interdicting the rebels. But Asiri did not rule out future airstrikes against the Houthi rebels.

The Saudi embassy in Washington released a statement Tuesday mirroring a series of remarks by Gen. Asiri, saying the military campaign had achieved its objectives, which included “the prevention of the flow of weapons from outside of Yemen into the country.”

Pentagon sources told Fox News that the USS Theodore Roosevelt, an aircraft carrier, is tracking an Iranian convoy as it approaches Yemen. The contents of the convoy’s cargo are not yet known, but the U.S. Navy said it was prepared to intercept any weapons shipments bound for the Yemeni rebel forces, known as Houthis.

The announcements from both Riyadh and Washington came after airstrikes from the Saudi-led coalition killed 20 people in Yemen, officials said.

Saudi Arabia accuses Iran of arming the Houthis -- a claim both Tehran and the rebels deny, though the Islamic Republic has provided political and humanitarian support to the Shiite group. For its part, the Shiite Iran has long accused Saudi Arabia of supporting Sunni militants, including the Islamic State group in Syria and Iraq.

In remarks Tuesday, Iranian President Hassan Rouhani said the airstrikes in Yemen were prompted by the Sunni kingdom's failures elsewhere, causing what he called a "mental imbalance."

Speaking to reporters before heading to Indonesia, Rouhani mocked Saudi Arabia by calling it a country with dashed dreams in Iraq, Syria and Lebanon.

"All the failures have accumulated and caused mental and emotional imbalance for that country," Rouhani said.

In addition to Rouhani, Iran’s Supreme Leader Ayatollah Khomenei tweeted that the “Saudis will suffer a loss and their noses will be rubbed in dirt over Yemen.”

In a later tweet, Khomenei wrote that the Saudis “made a mistake” in Yemen similar to what he claimed “Israel did to Palestine.”

The U.S.-backed campaign by Saudi Arabia and its allies, mainly Gulf Arab countries, is aimed at crushing the Houthi rebels, who have taken over Sanaa and areas in northern Yemen and have been pressing an offensive to expand their gains in the rest of the country, including the southern port city of Aden.

The ground fighting and the airstrikes have pushed Yemen, the Arab world's poorest country, to the brink of collapse. The fighting has also taken on the appearance of a proxy war between Iran, the Shiite powerhouse backing the Houthis, and Sunni-dominated Saudi Arabia.

On Tuesday, airstrikes hit a gathering of the Houthis in the western of Ibb, killing 20 fighters, security officials on the ground said.  The rebels were assembling to head to Aden as reinforcements in the battle against forces loyal to President Abed Rabbo Mansour Hadi, who fled the country from Aden to Saudi Arabia last month.

In Sanaa, death toll from of bombings Monday targeting rebel depots and weapon caches in the Fag Atan mountains overlooking the city rose to 38, medical officials said. The bombings flattened houses and sent villagers fleeing for their lives.

The rebel-controlled Interior Ministry said 84 people were killed across the country in Monday's airstrikes. The casualty figures could not be independently confirmed. All officials spoke on condition of anonymity because they were not authorized to speak to the media.

The deployment of the US carrier comes after a U.N. Security Council resolution last week imposed an arms embargo on Houthi leaders.

The Navy has been beefing up its presence in the Gulf of Aden and the southern Arabian Sea in response to reports that a convoy of about eight Iranian ships is heading toward Yemen and possibly carrying arms for the Houthis. Navy officials said there are about nine U.S. warships in the region, including cruisers and destroyers carrying teams that can board and search other vessels.

Later in the day, the official Saudi news agency reported that King Salman has ordered the country's National Guard to take part in the Yemen operation. There were no further details on the scope of the deployment but it appeared to be another step toward a possible ground invasion.

The Associated Press and Fox News’ Lucas Tomlinson contributed to this report.