WEST JERUSALEM, Israel - The Israel Air Force has launched a pre-emptive Pearl Harbour style air raid over Iran, dropping bombs over the capital Tehran and other cities.

The attack, involving more than 200 Israeli fighter jets, has come without warning, or provocation, and comes amid delicate negotiations between the United States and the Islamic State over Iran's nuclear aspirations.

Israel's Prime Minister Benjamin Netanyahu for more than two decades has been accusing Tehran of building a nuclear bomb, a claim Iran denies.

No evidence has emerged of Iran having any aspirations other than the pursuit of nuclear power for peaceful purposes. As part of a previous agreement, spearheaded by the Obama administration, Iran opened its nuclear facilities to the UN's Atomic Energy Agency which cleared Iran of any plans to weaponize its nuclear plants.

Nonetheless, the Israel Defense Forces (IDF) on Friday claimed Iran has sufficient uranium to assemble fifteen nuclear weapons "within days."

"Weapons of mass destruction in the hands of the Iranian regime are an existential threat to the State of Israel and to the wider world," the IDF said in a statement.

Mr Netanyahu was also at work in the early hours of Friday morning, streaming an announcement warning the attack could go on for as long as it takes.

"Moments ago, Irsaeli forces launched Operation Rising Lion targeting military operations to roll back the uranium threat to Israel's very survival. This operation will continue for as many days as it takes  to remove this threat," he said. 

"For decades the tyrants of Tehran, have brazenly., openly, called for Israel's destruction. They've backed up their genocidal rhetoric with a program to develop nuclear weapons."

"In recent years, Tehran has produced enough highly enriched uranium for nine atomic bombs. In recent months Iran has taken steps that it has never taken before, steps to weaponize enrihed uranium," the Israeli prime minister said. "If not stopped, Iran could produce a nuclear weapon in a very short time, it could be a year, it could be within a few months," he said.

Early reports say residential areas, including buildings housing military officials were targeted in the first phase of the attacks.

Iranian media have confirmed that the Iranian Armed Forces Chief of Staff, Major General Mohammad Bagher, and senior nuclear scientists were assassinated in the opening stages of the bombing raid. Hossein Salami, the commander of the Islamic Revolutionary Guard Corps; and Major-General Gholam Ali Rashid, commander of the Khatam al-Anbiya Central Headquarters were also assassinated, together with their families.

For years Israel has sabotaged construction of Tehran's nuclear plants, assassinating nuclear scientists and with the United States hacking into a nuclear plant's computer software, implementing the Stuxnet malware, a cyber operation targeting Iran's Natanz nuclear facility. The joint Mossad-CIA operation is considered one of the first major examples of cyber warfare. There were consequences however as the Stuxnet virus spread to several other countries, infecting tens of thousands of computer networks worldwide.

While the world, and even the Trump administration, has been pressuring Israel to ends its 20-months-long attack on Gaza and agree to an immediate and permanent ceasefire involving the return of the hostages, Israel instead has escalated its attacks on Gaza, and at the same time has broken a ceasefire in Lebanon and is now regularly carrying out attacks there, while accelerating attacks into Syria. Israel has also been launching airstrikes in Yemen, targeting the Houthis who have been firing on Israel.

The United States says it is not involved in Friday's attacks by the Jewish state, and is not providing support. It did not indicate however whether it was advised in advance of the attacks or is being updated on developments, although, in a telling sign, personnel at the U.S. embassy in Baghdad have been evacuated in the past 24-36 hours.

"Tonight, Israel took unilateral action against Iran. We are not involved in strikes against Iran and our top priority is protecting American forces in the region," U.S. Secretary of State Marco Rubio said in a statement early Friday morning (Israel time).

"President Trump and the administration have taken all necessary steps to protect our forces and remain in close contact with our regional partners. Let me be clear: Iran should not target US interests or personnel," Rubio warned.

The first stage of the unilateral attacks wound up early Friday morning. "Dozens of IAF jets completed the first stage that included strikes on dozens of military targets, including nuclear targets in different areas of Iran," an IDF statement said. "today, Iran is closer than ever to obtaining a nuclear weapon. Weapons of mass destruction in the hands of the Iranian regime are an existential threat to the State of Israel and to the wider world," the statement said.

"The State of Israel has no choice but to fulfill the obligation to act in defense of its citizens and will continue to do so everywhere it is required to do so, as we have done in the past," the IDF statement added.