US President Joe Biden speaks during a news conference with Japanese Prime Minister Fumio Kishida (L) in the Rose Garden of the White House in Washington. AP
Biden's promise comes despite his public criticism of Prime Minister Benjamin Netanyahu over the toll on civilians in Israel's war on Gaza, especially after a strike that killed seven aid workers.
Iran is "threatening to launch a significant attack on Israel," Biden told a news conference.
"As I told Prime Minister Netanyahu, our commitment to Israel's security against these threats from Iran and its proxies is ironclad," Biden said.
"Let me say it again, ironclad. We're going to do all we can to protect Israel's security," said Biden, who was speaking next to Japanese Prime Minister Fumio Kishida.
US officials have voiced alarm over the prospect of an imminent strike against Israeli interests after Israel on 1 April destroyed the consulate building in Syria, killing seven members of Iran's elite Revolutionary Guards, including two generals.
Iran's Supreme Leader Ayatollah Ali Khamenei warned in a speech Wednesday that the "evil regime" of Israel "must be punished and will be punished."
Israeli Foreign Minister Israel Katz riposted, in a Persian-language statement on social media site X: "If Iran attacks from its territory, Israel will respond and attack Iran."
The United States since the start of the Gaza war has sought to prevent it from spreading, including to Lebanon.
According to The Intercept, the White House is worried that Iran might strike a US target as part of a potential retaliation, according to notes from a meeting involving National Security Council officials earlier this week.
New concern about a potential Iranian strike comes even though the Biden administration has sought to distance itself from the Israeli airstrike, stressing that it had no advance knowledge of the operation.
The United States has been tight-lipped in its public reaction to the April 1 strike, saying it has not determined whether Israel struck a diplomatic facility, which would breach international agreements on the inviolability of embassies and consulates.
“I don’t have anything more to say about the strike in Damascus, except that we weren’t involved in any way whatsoever,” NSC spokesperson retired Adm. John Kirby said on Monday.
On Monday night, Iran conveyed to the Biden administration that if it helped defend Israel from Iranian retaliation, Tehran would consider the United States a viable target as well.
The issue was discussed at a Tuesday NSC meeting, according to notes reviewed by The Intercept.
At the Tuesday meeting, an NSC official conveyed high-level concerns that the administration did not want to publicly appear to be in any official dialogue with Tehran, with whom the US does not have formal diplomatic relations.
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