• Iran launched a ballistic missile attack on Israel, the Israeli military said.
• President Joe Biden and Vice President Kamala Harris met with national security officials at the White House to review the status of U.S. preparations to help Israel defend against attacks.
• The attack comes after Israeli ground forces entered southern Lebanon to attack the militant group Hezbollah.
• The Dow Jones Industrial Average fell more than 250 points, spurred by a surge in the cost of WTI crude oil, on fears of heightened tensions in the petroleum-rich Middle East.

Iran on Tuesday launched a ballistic missile attack on Israel in retaliation for its recent killing of Hezbollah leader Hassan Nasrallah and an Iranian general in Lebanon.

The attack came on the heels of Israel's deployment of ground forces into south Lebanon, escalating its attack on Hezbollah, a militant group backed by Iran.

"In response to the martyrdom of Martyr Haniyeh, Seyyed Hassan Nasrallah, and Martyr Nilforoushan, we have targeted the heart of the occupied territories," the Islamic Revolutionary Guard Corps said in a statement after missiles began appearing in the skies over Israel.

"Should the Zionist regime respond to Iran's operation, it will face crushing attack," the IRGC said.

A White House official warned that any direct attack on Israel by Iran "will carry severe consequences for Iran."

"We are actively supporting defensive preparations to defend Israel against this attack," the official said.

That official and a Defense Department official said that Iran was expected to target military and government sites, not civilian locations.

Sirens wailed around Israel during Tuesday's attack.

President Joe Biden met Tuesday afternoon with Vice President Kamala Harris and national security officials to discuss the expected attack, the White House said.

"They reviewed the status of U.S. preparations to help Israel defend against attacks and protect U.S. personnel," White House senior deputy press secretary Emilie Simons said in a post on the social media site X.

The U.S. Embassy in Jerusalem directed all U.S. government employees and their families in Israel to "shelter in place until further notice."

The embassy in the same notice said it "reminds U.S. citizens of the continued need for caution and increased personal security awareness as security incidents, including mortar and rocket fire and unmanned aircraft system UAS intrusions, often take place without warning."

"The security environment remains complex and can change quickly depending on the political situation and recent events," the notice said.

Iran's suspected planned attack came as Israeli ground forces crossed into south Lebanon as part of an attack on Hezbollah, the militant group backed by Iran. The number of Israeli troops who have entered Lebanon is in "the low hundreds," an Israeli official told NBC News.

Israel last week killed Hezbollah chief Hassan Nasrallah in a bombing in Beirut.

Iran Foreign Minister Abbas Araghchi said the killing of Nasrallah and a senior Revolutionary Guards commander in that attack "will not go unanswered." Araghchi said the United States was "complicit in this crime."

The Dow Jones Industrial Average fell more than 250 points by 10 a.m. ET, spurred by a surge in the cost of West Texas Intermediate crude oil, on fears of heightened tensions in the petroleum-rich Middle East.

The WTI November contract was up nearly 3% by midmorning, hovering shy of $70 a barrel.

In April, Iran launched an attack on Israel that included more than 300 drones and ballistic missiles after two top Iranian commanders were killed by an Israeli airstrike in Syria.

Most of the missiles and drones were shot down by the Israeli and U.S. militaries.

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