The United States is setting up a round-the-clock task force to help Americans in the Middle East during the Israel-Iran conflict, officials said Tuesday.

U.S. President Donald Trump met his National Security Council on Tuesday to discuss the Iran-Israel war, the White House said, as the U.S. leader considered whether to join Israel's air campaign against Tehran.

Israel said it struck a nuclear site near Tehran on Wednesday, while Iran said it fired hypersonic missiles as the arch foes traded fire for a sixth day.

Hours after U.S. President Donald Trump demanded Iran's surrender, supreme leader Ayatollah Ali Khamenei vowed his country would show "no mercy" towards Israel's leadership.

U.S. President Donald Trump dramatically stepped up his rhetoric against Iran's supreme leader Tuesday, saying on social media that the United States knows where Ayatollah Ali Khamenei is located but will not kill him "for now."

In another post, Trump also appeared to demand Iran's "UNCONDITIONAL SURRENDER!" as he fueled questions about whether the United States would join Israel's attacks on Tehran's leadership and nuclear facilities.

Air raid sirens sounded in the Tel Aviv area and parts of northern Israel on Tuesday, the military said, after warning of a fresh salvo of incoming missiles fired from Iran.

"A short while ago, sirens sounded in several areas across Israel following the identification of missiles launched from Iran toward the state of Israel," a statement from the military said, with residents of the Tel Aviv area and parts of the north urged to seek shelter.

There appear to have been "direct impacts" on the underground part of Iran's Natanz nuclear site during Israel's attacks, the U.N.'s atomic watchdog said on Tuesday.

"Based on continued analysis of high resolution satellite imagery collected after Friday's attacks, the IAEA has identified additional elements that indicate direct impacts on the underground enrichment halls at Natanz," the International Atomic Energy Agency said on X, formerly Twitter.

Twenty countries denounced in a joint statement the escalating tensions in the Middle East caused by what they term Israel’s aggression against Iran and called for diplomacy and dialogue to restore stability in the region.

“There’s an imperative need to halt Israeli hostilities against Iran, which come during a time of increasing tension in the Middle East, and to work towards de-escalation, to achieve a comprehensive ceasefire and restoration of calm,” read the statement.

Iran's Revolutionary Guards said they struck a center of Mossad, Israel's foreign intelligence service, in Tel Aviv on Tuesday, amid an escalating air war between the two foes.

In a statement aired on state television, the Guards said they "struck the military intelligence centre of the Zionist regime's army, Aman, and the Zionist regime's terrorist operations planning centre, the Mossad, in Tel Aviv", adding it was "currently on fire".

U.S. President Donald Trump said Tuesday he was aiming for a "real end" to the conflict between arch-rivals Israel and Iran, and not just a ceasefire.

"I'm not looking for a ceasefire, we're looking at better than a ceasefire," Trump told reporters on board Air Force One before arriving back in the United States from a G7 summit in Canada.

Iran's Foreign Minister and chief nuclear negotiator Abbas Araghchi said Israel's strikes against his country "deal a blow" to diplomacy during a call Monday with his French, British, and German counterparts.

"The Israeli aggression against Iran in the midst of nuclear negotiations with the United States is a blow to diplomacy," Abbas Araghchi said during a call reported by his ministry with French Foreign Minister Jean-Noel Barrot, the United Kingdom's David Lammy, Germany's Johann Wadephul, and the European Union's head of foreign affairs Kaja Kallas.