The United States is the main international backer of Israel, Iran's biggest regional foe. It is also a close ally of Sunni Gulf monarchies which for years pursued their own rivalry with the Islamic Republic, seeing it as their main regional threat.

Israel’s military struck Tehran and other targets early Friday morning, raising fears of a broader war. The U.S. said it was not involved in the strikes.

Israeli officials were initially concerned that US President Donald Trump's Thursday evening comments, suggesting Israel "might attack," alerted the Iranians.

Israeli Prime Minister Benjamin Netanyahu described the operation as a “decisive moment in Israel’s history,” vowing that the attacks would continue for days.

President Donald Trump's administration sought to distance the United States on Thursday from Israel's strikes on Iran, attacks that are likely to complicate Trump's drive for a nuclear deal with Tehran.

The United States has denied any involvement in Israel's recent strikes against Iran, with Secretary of State Marco Rubio stating that the operation was unilateral and undertaken by Israel.

Israel’s overnight missile strike was the largest attack on the Islamic Republic since the Iran-Iraq war of the 1980s.

The push by the Trump administration to persuade Tehran to give up its nuclear program came after the U.S. and other world powers in 2015 reached a long-term, comprehensive nuclear agreement that limited Tehran’s enrichment of uranium in exchange for the lifting of economic sanctions.

The United States has pulled some diplomatic staff and military families out of the Middle East, citing unspecified regional security risks.

As the head of the secretive Islamic Revolutionary Guard Corps (IRGC) Major General Hossein Salami, was one of the most powerful men in Iran, overseeing its most potent military arm and reporting directly to its Supreme Leader Ayatollah Ali Khamenei.