A photo distributed by the Houthi Military Media Unit shows the launch by Houthi forces of a ballistic missile aimed at Saudi Arabia on March 25, 2018. Photo: Houthi Military Media Unit / Handout via Reuters.

Saudi Arabia‘s air defense forces intercepted at least three ballistic missiles fired at Saudi cities by Yemen’s Houthis, who claimed to have targeted the Defense Ministry in Riyadh and a Saudi Aramco distribution facility in Najran on Wednesday.

Three rockets were intercepted in the capital and the southern cities of Jizan and Najran, according to state media and the Saudi-led coalition fighting the Iran-aligned Houthis in Yemen.

There were no immediate reports of damage or casualties.

The attacks mark the fourth time in five months that missiles have flown over Riyadh, as the Houthis step up efforts to demonstrate they can reach the Saudi capital, threatening to escalate a regional rivalry between Iran and Saudi Arabia.

The missiles followed the downing of two Houthi drones earlier on Wednesday in Jizan and the nearby Saudi city of Abha, the coalition said. The Houthis said they were targeting an Aramco facility in Jizan, but the company said its facilities there were operating “normally and safely.”

The company is building a 400,000-barrel-per-day refinery in Jizan, part of a new economic city on the Red Sea, which is expected to become fully operational in 2019.

Aramco was not immediately available for the comment on the missiles.

Yemen’s Houthis say missile attacks on the kingdom are in retaliation for air raids on Yemen by the Western-backed coalition.

Last month, one man was killed in Riyadh by debris after the military shot down a flurry of missiles, the first casualty of the Yemen war in the Saudi capital.

Saudi Arabia and a coalition of Muslim states intervened in Yemen’s civil war in 2015 to try and push back the Houthis after they drove the internationally recognized government into exile in Riyadh.

The coalition has launched thousands of air strikes in Yemen which have hit schools, markets and hospitals, killing hundreds of people – though it says it does not target civilians.

The United Nations says 10,000 people have died in the three-year-old war, and three out of four Yemenis — 22 million civilians — need relief aid.

The coalition accuses the Houthis of being armed and supported by Iran — charges the group and Tehran deny.

The arms monitor Conflict Armament Research says it has evidence that the drones used on Wednesday and other Houthi kit was made in Iran and was not of indigenous design and construction “in contrast to Houthi statements.”