Saudi Arabian city hit by Houthi missile strike
Yemen's Houthis say they struck a power station in Saudi Arabia's Al-Shuqaiq city with a cruise missile on Wednesday, but Riyadh said that a projectile had landed near a desalination plant, causing no casualties or damage.
In a statement carried by the Saudi state news agency SPA on Thursday, the coalition said security forces were working to determine what type of projectile had been used.
US officials said they were aware of reports of a missile strike on the kingdom's "critical infrastructure", but gave no details of possible damage or casualties.
Al-Shuqaiq is located in the southern Saudi province of Jizan.
The Houthis, who ousted the Saudi-backed internationally recognised government from power in Sanaa in late 2014, have stepped up missile and drone attacks on Saudi Arabia in response to the kingdom's ongoing air strikes against rebel areas of Yemen.
In Washington, White House spokeswoman Sarah Sanders said President Donald Trump had been briefed on the reports of a missile strike in Saudi Arabia.
"We are closely monitoring the situation and continuing to consult with our partners and allies," she added.
'Significant cause for concern'
Pentagon spokeswoman Navy Commander Rebecca Rebarich said such attacks were "a significant cause for concern and [put] innocent lives at risk".
The Yemen conflict is widely seen in the region as a proxy war between Saudi Arabia and Iran, but the Houthis have denied taking any orders from Tehran and say they took up arms against corruption.
Washington and Riyadh have blamed Tehran for attacks on two oil tankers in the Gulf of Oman last week and four ships off the United Arab Emirates last month, both near the Strait of Hormuz, a major conduit for global oil supplies.
Iran has denied responsibility.
The Houthis also targeted two Saudi oil pumping stations last month, and a Houthi attack last week on Saudi Arabia's Abha airport wounded 26 people, Saudi authorities said.
A US official said on Thursday that a US military drone had been shot down in international airspace over the Strait of Hormuz by an Iranian surface-to-air missile.
The official, speaking on condition of anonymity, said the drone was a US Navy MQ-4C Triton, the Reuters news agency reported.
No further details were immediately available, including the time of the downing.
Earlier, Iran's elite Revolutionary Guards said it shot down a US "spy" drone in the southern province of Hormozgan, which borders the Strait of Hormuz, the Guards' news website Sepah News said.
The US military has in recent weeks sent forces including aircraft carriers, B-52 bombers and troops to the Gulf.