Israel unleashed airstrikes across Iran for a third day on Sunday and threatened even greater force as some Iranian missiles evaded Israeli air defenses to strike buildings in the heart of the country.

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.”

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.

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.

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.

Experts suggest the U.S. has a strategic opportunity to leverage Iran's weakened position for a nuclear deal after Israel's targeted strikes on Iranian nuclear and military sites.

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

Israel's operation against Iran is projected to last "weeks, not days," with implicit US approval, according to White House and Israeli officials.