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.

WASHINGTON, UNITED STATES - Donald Trump warned Iran on Sunday that it would experience "the full strength" of the US military if it attacks the United States, reiterating that Washington "had nothing to do" with Israel's strikes on Tehran's nuclear and intelligence facilities.

President Donald Trump said early on Sunday that if Iran attacks the United States in any way, it would face the might of the US military “at levels never seen before.”

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

Countries trade strikes as tensions grow over larger Middle East conflict - Iranian missiles struck an apartment building in the Galilee region, killing four people, as the countries exchanged fire

In sweeping attacks that started early Friday, Israel has struck at the regime in Tehran, targeting Iranian nuclear and military assets. The Israeli strikes have killed more than 70 people, including four top security chiefs, and damaged Iran’s main nuclear site at Natanz.

Iranian officials said on Friday that the United States "shall be held fully accountable" for its support of Israel after the nation took out key Iranian nuclear facilities and killed government leaders in a series of air strikes this week.