Jewish Currents: Iran Is Not an Existential Threat - Iran poses no significant danger to Israel, let alone the US.

I recommend this very cogent article in Jewish Currents. I quote

It wasn’t until the 1990s that Israeli and American leaders began describing Iran as a threat to the Jewish state. But this change in rhetoric didn’t occur because Iran’s attitude toward Israel changed. It occurred because Iraq, Israel’s chief bogeyman, had been brought to its knees. With Saddam Hussein hobbled by the 1991 Gulf War and then a decade of brutal US sanctions, the Islamic Republic took its place as Israel’s foremost regional competitor. “Nothing special happened with Iran,” retired Israeli Brigadier General Shlomo Brom told Parsi, “but because Iraq was removed [as a danger], Iran started to play a greater role in the threat perception of Israel.”
To be sure, Iran did grow stronger in the ’90s as a result of Iraq’s decline. It also began backing Hamas and Islamic Jihad, which opposed the Palestine Liberation Organization’s recognition of Israel. And in the early 1990s, Iran restarted its nuclear energy program, which had begun under the Shah. It was this cocktail—Iran’s hostile rhetoric, its nuclear program, and its support for armed anti-Zionist groups—that birthed the current conventional wisdom that Iran represents an existential threat to Israel.

But this claim has never been borne out by Iranian behavior. Despite its antipathy toward Zionism, and its efforts to resist Israeli and American power, the Iranian regime has shown no willingness to imperil itself by trying to destroy Israel. To the contrary, it has repeatedly sought to defuse conflict with both Jerusalem and Washington, if only because it recognizes their vastly superior power. In May 2003, after the Bush administration’s invasions of Afghanistan and Iraq, Iran sent the US government a secret message: If the US lifted sanctions, ceased trying to overthrow the Islamic Republic, and accepted Tehran’s right to peaceful nuclear energy, Iran would end its support for Hamas and Islamic Jihad, pressure Hezbollah to disarm, place its nuclear program under international inspection, and support the 2002 Arab Peace Initiative, which offered to recognize Israel if it accepted a Palestinian state and a “just solution to the Palestinian refugee problem.” According to Richard Haass, then head of policy planning at the State Department, the Bush administration spurned Tehran’s offer because “the bias was toward a policy of regime change.”