Iran aims 'devastating and powerful' attack at U.S. airbase in Qatar

Iran's military said on Monday it had carried out a "devastating and powerful" missile attack on the Al Udeid U.S. airbase in Qatar, after explosions were heard across the Qatari capital following Tehran's threat to retaliate for U.S. airstrikes.

Iran had issued threats to retaliate against the United States after U.S. bombers dropped 13,500-kilogram 'bunker-busters' on Iranian underground nuclear sites at the weekend, joining Israel's air war against Tehran, and President Donald Trump mooted the possibility of the Iranian government being toppled.

Qatar's defense minister, quoted by Al Jazeera TV, said its air defenses had intercepted missiles directed at the Al Udeid airbase, the largest U.S. military installation in the Middle East, situated across the Gulf from Iran.

Qatari authorities said there were no casualties in the attack, which it condemned and said it reserved the right to respond.

The attack came shortly after a Western diplomat told Reuters there had been a credible threat to a U.S. military base in the Gulf state following the U.S. airstrikes on Iran.

In addition, the U.S. Ain al-Asad air base in Iraq had activated its air defense system out of concern of a potential attack, military sources told Reuters.

The White House and the Defense Department are closely monitoring potential threats to the Al Udeid airbase, a senior White House official said in Washington on Monday.

Shortly before, Qatar, a small, wealthy Gulf Arab state, announced it had closed its air space temporarily to ensure the safety of residents and visitors. That followed an advisory from the U.S. embassy in Qatar to Americans to shelter in place, out of what it said was "an abundance of caution".

Two U.S. officials said Washington had assessed that Iran could carry out attacks targeting American forces in the Middle East soon, although the U.S. was still seeking a diplomatic resolution that would see Tehran forgo any reprisal.

Earlier on Monday, Israel bombed a jail for political prisoners in Tehran in a potent demonstration that it was expanding its targets beyond military and nuclear sites to aim squarely at the pillars of Iran's ruling system.

Despite Iran's threats to challenge oil shipments from the Gulf, oil prices largely held steady, suggesting traders doubted the Islamic Republic would follow through on any action that would disrupt global supplies.