Yemen's Houthi rebels said Tuesday they launched a bomb-laden drone targeting an airport in Saudi Arabia that also has a military base inside of it, an attack acknowledged by the kingdom as Mideast tensions remain high between Iran and the U.S.

In the drone attack, the Houthi's Al-Masirah satellite news channel said early Tuesday they targeted the airport in Najran with a Qasef-2K drone, striking an “arms depot” there. Najran, 840 kilometers southwest of Riyadh, is right on the Saudi border with Yemen and has repeatedly been targeted by the Iranian-allied Houthis.

A statement earlier Tuesday on the state-run Saudi Press Agency quoted Saudi-led coalition spokesman Col. Turki al-Maliki as saying the Houthis “had tried to target” a civilian site in Najran, without elaborating. It was not clear if there were any injuries.

Al-Maliki warned there would be a “strong deterrent” to such attacks and described the Houthis as the “terrorist militias of Iran.” Such Houthi attacks in the past have sparked rounds of Saudi-led airstrikes on Yemen, which have been widely criticized internationally for killing civilians.

The attack on Najran comes as Iran quadrupled its uranium-enrichment production capacity amid tensions with the U.S. over Tehran's atomic program, nuclear officials said Monday, just after President Donald Trump and Iran's foreign minister traded threats on Twitter.

The state-run IRNA news agency later quoted Behrouz Kamalvandi, the spokesman of the Atomic Energy Organization of Iran, as acknowledging that capacity had been quadrupled. He said Iran took this step because the U.S. had ended a program allowing it to exchange enriched uranium to Russia for unprocessed yellowcake uranium, as well as ending the sale of heavy water to Oman. Heavy water helps cool reactors producing plutonium that can be used in nuclear weapons.

Iranian officials made a point to stress that the uranium would be enriched only to the 3.67 percent limit set under the 2015 nuclear deal with world powers, making it usable for a power plant but far below what's needed for an atomic weapon.

(Cover: The fast combat support ship USNS Arctic transports cargo to the Nimitz-class aircraft carrier USS Abraham Lincoln during a replenishment-at-sea in the Arabian Sea, May 19, 2019. /AP Photo)