Iran’s supreme leader Ayatollah Ali Khamenei said bluntly on Wednesday: “The Americans should know that any US military intervention will undoubtedly be accompanied by irreparable damage."
It was an emphatic warning to the world’s mightiest superpower, made all the more remarkable by the fact that only days ago US President Donald Trump was touting high-level talks with Iran to secure a nuclear deal.
Mr Khamenei’s comments came amid signs of the US becoming more open to joining Israel’s air campaign, which would be a massive escalation that many in the international community, from France to Russia, warn would have a dramatic effect on Middle East stability.
Despite the risks, there is widespread agreement in Israel that if Iran’s nuclear capabilities are to be fully destroyed, the US must take part, because only Washington possesses bunker-busting bombs that can reach the underground depths of the Fordow nuclear complex.
Mr Trump met advisers in the Situation Room at the White House on Tuesday, shortly after returning early from the G7 summit in Canada over the escalating Middle East hostilities. The President wrote on his Truth Social platform "we know exactly where the so-called ’Supreme Leader’ is hiding”.
“He is an easy target, but is safe there – we are not going to take him out (kill!), at least not for now. But we don’t want missiles shot at civilians, or American soldiers. Our patience is wearing thin."
In Israel, a press report has emerged that Israeli Prime Minister Benjamin Netanyahu and Defence Minister Israel Katz believe the US will join the fight in a matter of days. “Trump is seriously considering attacking Iran,” said someone described as “a senior Israeli source”.
“[Mr Trump] will want to be remembered as someone who took part and didn't stay on the sidelines,” the source reportedly added.
Despite Mr Netanyahu being on the brink of a collapse in his governing coalition shortly before the Iran campaign, all domestic political tension in Israel appear to have been put on hold. The country’s opposition leader Yair Lapid also called for the US to join the fighting.
In a video on Wednesday at the site of an Iranian missile strike in Herzliya, north of Tel Aviv, Mr Lapid said: “I trust President Trump to do what’s right for the US, but in talks with international officials and in the international press I repeatedly say – the US must join this battle. A nuclear Iran is a threat to the entire world, not just Israel.”
Israeli newspaper The Jerusalem Post argued in an editorial that "Trump needs to take decisive action".
"Mr President, this extreme theocracy needs to fall. Make its destruction as explicit a policy as the defeat of Nazi Germany or Saddam Hussein’s Iraq," it said.
"Harness every tool of American power, be it diplomatic, economic, covert, or militarised, to dismantle Ayatollah Khamenei’s regime before it can realise its vow to erase Israel and America from the map. Only then can the region breathe free of tyranny and terror, and the cancer of radical theocracy be excised once and for all."
The US has been moving significant numbers of aircraft closer to the Middle East. These include flying refuelling tankers and C17 aircraft to US bases in Europe, according to open-source monitoring group Aurora Intel. Earlier, Mr Trump had moved a dozen F-16 fighter jets to a base in Saudi Arabia, the group said.
Former Israeli national security adviser Yaakov Amidror told The National that US participation would be pivotal for Israel in destroying Fordow.
“It’s not about the wider war but a very specific place, Fordow, around which Israel has cleared Iranian anti-air defence systems [for a potential US strike],” Mr Amidror said.
Outside of this, “basically Israel doesn’t need [the Americans],” Mr Amidror added. If the US did not join, he believed Israel’s air force would find “a solution because we have full control of Iran’s skies”.
“What exactly, I don’t know,” he said.
