US President Joe Biden said he is in talks with Israel about possible retaliatory strikes on Iranian oil facilities after publicly opposing targeting Tehran's nuclear facilities.
In comments made to reporters about the potential strike package on Thursday Biden said: "We're discussing that. I think that would be a little… anyway."
He said the US "advises" rather than allows Israel to conduct such attacks, amid mounting speculation about a military response to Iran's ballistic missile attack on 1 October.
Some 200 missiles were used by Iran in the attack striking sites around Tel Aviv and causing damage at the Nevatim base in the Negev (Naqab) Desert.
The attack prompted immediate threats by Israel, with military spokesperson Daniel Hagari warning that "there will be consequences", while Israel's Channel 12 quoted unnamed ministerial sources as saying Israel's response would be "significant".
Israeli officials have conveyed to the US that an immediate and massive retaliation is not needed, according to The Wall Street Journal.
Biden ruled out support for targeting Iran's nuclear facilities on Tuesday in comments made to journalists.
Former Israeli Prime Minister Ehud Barak said that Israel could launch an attack against oil facilities alongside an attempt to strike nuclear facilities.
In an interview with The Guardian, Barak said that there was pressure within the Israeli government to commit to such a strike, even if it would not substantially affect Tehran's nuclear programme, which Israel and its allies believe has military aims.
Within the US, Republican Senator Lindsey Graham criticised Biden and G7 comments over calling for a proportional response, advocating for a harsh response in hawkish comments made to The Jerusalem Post.
Iran has warned the US that any Israeli strike on its territory would be met with an "unconventional response" according to Al Jazeera.
The official told the outlet that Iran had passed a message to the US through Qatar, warning that "the phase of unilateral self-restraint has ended". The remarks were caveated with an emphasis that Iran does not seek a regional war.
Iran's mission to the UN warned that any country that assists an Israeli attack would be targeted in retaliatory actions.
Tehran is already making preparations for an Israeli response on its territory, with two Iranian officials telling The New York Times that it has requested cooperation from Russia with satellite intelligence.
In an address at Friday prayers, Iran's Supreme Leader Ayatollah Ali Khamenei said that neither Iran nor its allies in the region would back down against Israel.
Echoing Khamenei's warning, Deputy Commander of the Revolutionary Guard, Brigadier General Ali Fadavi vowed to retaliate to attacks on Iran's oil facilities with similar strikes on Israel's energy sector.
In a press conference in Beirut, Foreign Minister Abbas Araghchi warned that whilst Iran was engaging with Lebanese officials on a ceasefire for both Lebanon and Gaza, any Israeli response against Tehran would warrant a stronger retaliation.