Iran says it fired on a US base. Qatar says air defenses shot down the missiles.

• Iran said it launched several missiles at a large US military base in Qatar on Monday.
• The attack follows the US bombing of Iran's nuclear facilities over the weekend.
• President Donald Trump has warned Tehran that it will hit back harder after any retaliation.

Iran said it launched missiles at the US military's largest Middle East base, Al Udeid Air Base in Qatar, just days after American forces struck its nuclear facilities.

A US defense official confirmed to Business Insider Monday afternoon that Iran launched short-range and medium-range ballistic missiles at Al Udeid. They said there are no reports of US casualties and that the Pentagon is monitoring the situation closely.

Iranian state media said Tehran launched the same number of missiles as the number of bombs that the US used against its nuclear facilities, and called the strikes "a mighty and successful response by the armed forces of Iran to America's aggression."

Qatar's foreign ministry also confirmed the attack on Al Udied and described it as a violation of its sovereignty. Doha said its air defenses "successfully thwarted" the strikes, intercepting Iranian missiles.

Open-source accounts online shared footage purporting to show air defenses engaging targets over Qatar. Some Iranian media reported the targeting of American forces in Iraq, although there has not been any official confirmation from the Pentagon.

The US Air Force and US Central Command, which oversees Middle East operations, did not immediately comment on the Iranian attack.

Satellite imagery of Al Udeid last week showed dozens of military aircraft missing from the base after around 40 were spotted there earlier in the month. The air base supports a vast array of US aircraft, including B-52 strategic bombers, C-17 Globemaster transports, and RC-135 Rivet Joint reconnaissance aircraft.

It's unclear if any of the aircraft returned. Although the planes may no longer be there, US military personnel would still likely be on base.

Tehran had suggested that it could retaliate after US stealth bomber aircraft and a guided-missile submarine launched airstrikes against three Iranian nuclear facilities over the weekend. Its foreign minister said the country "reserves all options" to defend itself.

Earlier on Monday, the US Embassy in Qatar warned Americans to shelter in place until further notice, just hours before Doha closed its airspace, suggesting that an attack could be imminent.

President Donald Trump had warned Iran that any retaliation against the US would be met with more force than the initial strikes. It's possible that the attack on Al Udeid may have been calibrated to signal Iran's frustration while avoiding escalation.

"Our forces remain on high alert and are fully postured to respond to any Iranian retaliation or proxy attacks, which would be an incredibly poor choice," Gen. Dan Caine, the chairman of the Joint Chiefs of Staff, told reporters on Sunday.

The US military has a large Middle East presence that is capable of air defense, including ground-based missile interceptors, fighter jets, warships, and aircraft carriers. Those assets can be used for defensive actions, as well as offense.