Building hit at Soroka had been evacuated the day before

Iran's main targets in Thursday morning’s missile attack were the Israeli military’s command and intelligence headquarters, as well as an intelligence camp located near Soroka hospital in southern Israel, Iran’s state news agency IRNA reported.

Israeli ambassador to the United States Yechiel Leiter told CNN on Wednesday that the Jewish state was considering various options to attack the Fordow underground nuclear site, including "surprises".

“It might require multiple strikes, it might require something else or it might require one of our surprises,” Leiter said. “We have a few tricks up our sleeves."

“If we have to pursue this and prosecute this by ourselves, we’re going to know what to do," he added. "We’re not going to allow Iran to have a nuclear weapon.”

Grand Ayatollah Ali al-Sistani, a veteran Iraqi cleric who is one of the preeminent authorities in Shi'ite Islam, condemned attacks against Iran and called any killings of its leaders "criminal".

The top cleric "once again strongly condemned the continued military aggression against the Islamic Republic of Iran, as well as any threats of assassination targeting the country's top religious and political leadership," his office said in a statement.

"He firmly warned that any such criminal acts — in addition to being blatant violations of religious and moral principles and a clear breach of international norms and laws — would have extremely grave consequences for the entire region," it added.

"It could potentially lead to a complete loss of control over the situation and trigger widespread chaos, further deepening the suffering of the region's peoples and severely endangering the interests of all."

"Iran has now been offline for over 12 hours as authorities impose a nation-scale internet shutdown, citing Israel's alleged 'misuse' of the network for military purposes," the internet observatory NetBlocks said early Thursday.

"The measure continues to hinder residents' access to information at a critical time," it added.

As US President Trump appeared poised to attack Iran, top Senate Democrats have issued a joint statement accusing the administration of “a lack of preparation, strategy, and clearly defined objectives”.

“Congress is an equal partner in preserving and defending U.S. national security around the world, and Congress has not provided authorization for military action against Iran — we will not rubberstamp military intervention that puts the United States at risk,” five senior Democratic senators wrote.

They comprised Minority Leader Chuck Schumer, Chris Coons, Mark Warner, Jack Reed and Patty Murray.

“The United States cannot sleepwalk into a third war in as many decades,” they added.

“By law, the president must consult Congress and seek authorization if he is considering taking the country to war," the senators wrote. "He owes Congress and the American people a strategy for U.S. engagement in the region."

“We need a clear, detailed plan outlining the goals, risks, cost, and timeline for any proposed mission."