Khamenei said Iran’s enemies, including Israel and the US, “will definitely receive a crushing response to what they are doing to Iran, the Iranian people, and the resistance front”.
Iran’s so-called “axis of resistance” is an alliance of Tehran-backed groups that include Hamas in Gaza, Hezbollah in Lebanon, the Houthis in Yemen, and well-armed groups in Iraq and Syria. Most have been designated as terrorist entities by some Western states.
Israel is said to have inflicted severe damage on Iranian air defences and missile capacities in its 26 October attack, even though Iran has not admitted this.
Israel sees Iran as the crucial backer of the Hamas attacks which killed about 1,200 people on 7 October last year.
More than 250 were also taken into the Gaza Strip as hostages.
Since then, Israel has launched a major operation in Gaza, during which more than 43,300 people have been killed, according to the territory’s Hamas-run health ministry.
Israel also went on the offensive against Hezbollah in Lebanon in September, after almost a year of cross-border fighting and rocket fire, which Hezbollah had launched in support of Palestinians the day after the Hamas attacks.
Israel said it wanted to ensure the safe return of tens of thousands of residents from northern Israel displaced by the conflict.
More than 2,800 people have been killed in Lebanon since then, and 1.2 million others displaced, according to Lebanese authorities.
Israeli authorities say more than 60 people have been killed by Hezbollah rocket, drone, and missile attacks in northern Israel and the occupied Golan Heights.
Relations between the US and Iran have not properly stabilised since 4 November 1979, when Iranian protesters seized more than 50 US diplomats and embassy staff, triggering a hostage drama that lasted 444 days.