RIYADH (Reuters) – Saudi Arabia’s defence minister on Thursday accused Iran of ordering an attack on Saudi oil installations that Yemen’s Iran-aligned Houthi militia has claimed responsibility for. The attack “proves that these militias are merely a tool that Iran’s regime uses to implement its expansionist agenda,” Vice Minister of Defense Prince Khalid bin Salman, a son of King Salman, said in a tweet. “The terrorist acts, ordered by the regime in Tehran, and carried out by the Houthis, are tightening the noose around the ongoing political efforts.” The Houthi movement, which has been battling a Saudi-led military coalition in Yemen for four years, said it carried out Tuesday’s drone strikes, which Riyadh said did not disrupt output or exports. Other Saudi officials fired off similar tweets, ratcheting up pressure on the country’s arch enemy in the region at a time of heightened tension between Washington and Tehran over sanctions and the U.S. military presence in the Gulf. “The Houthis are an integral part of the Revolutionary Guard forces of Iran and follow their orders, as proven by them targeting installations in the kingdom,” Saudi Minister of State for Foreign Affairs Adel al-Jubeir said in a Twitter post. The drone attack came two days after Saudi oil tankers were sabotaged off the coast of the United Arab Emirates. The UAE has not blamed anyone for that incident, which is being investigated and from which Iran has distanced itself. In all four vessels, including a Norwegian-registered oil products tanker and a UAE-flagged bunker barge, were damaged. The Houthis have hit Saudi cities with drones and missiles, but two Saudi sources have told Reuters this was the first time a facility of the state-run Aramco had been attacked by drones.