Tehran, Iran - Israel launched airstrikes on Iran early on Saturday, with US forces reportedly participating in the unprovoked attack.

"The State of Israel has launched a preemptive strike against Iran. Defence Minister Israel Katz has declared a special and immediate state of emergency throughout the country," read a statement from his ministry.

A US official told Al Jazeera that Washington was participating in the attack, and President Donald Trump confirmed the start of full-blown war in an eight-minute speech.

Two loud blasts were heard in Tehran on Saturday morning by AFP journalists, and two plumes of thick smoke were seen over the center and east of the Iranian capital. Explosion were also reported in other regions of the country, with the Israeli army announcing that government buildings and military installations were being targeted.

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Both Israel and Iran announced the closure of their respective airspaces, as did other states in the region.

Iran responded by launching extensive retaliatory missile attacks. Qatar, which hosts the largest US military base in the Middle East, said it had intercepted a rocket. Bahrain, the United Arab Emirates, Kuwait, and Iraq – all countries with a significant US military footprint – have also reportedly come under fire.

The major escalation came after weeks of threats of war made by President Donald Trump, even as Iran had been participating in intense talks related to its nuclear program. As recently as Friday, officials from Tehran had made guardedly optimistic noises about progress towards a negotiated settlement.

Saturday's opening salvo mirrored the events of June last year, when Israel launched unilateral and unprovoked attacks on Iran while it was engaged in negotiations with Washington.

This is a developing story. More to follow.