US President Joe Biden ordered the military on Tuesday to "aid Israel's defence" and shoot down Iranian missiles targeting Israel, the White House said.
Biden and Vice President Kamala Harris, the Democratic nominee in next month's US presidential election, are both monitoring Iran's attack on Israel from the White House situation room, it said.
"President Biden directed the US military to aid Israel’s defence against Iranian attacks and shoot down missiles that are targeting Israel," the White House said in a statement.
A call that Biden had scheduled with rabbis on Tuesday ahead of the Jewish high holiday season -- which begins later this week with Rosh Hashanah, the Jewish new year -- had been postponed to another day, a White House official said.
The United States and other western allies also stepped in to help defend Israel against a combined Iranian missile and drone attack in April, which Tehran launched in retaliation for an Israeli strike on the Iranian consulate in Damascus.