After a massive Iranian attack of some 180 ballistic missiles this week, Israel is weighing a potentially deadly response.
The pending Israeli attack is stirring up a debate in Washington, with some arguing it was fair game to hit Iran's nuclear sites.
"Iran is not trying to build peaceful nuclear power plants," said Sen. Lindsey Graham (R-S.C.) in a statement. "The idea of telling Israel what targets to strike ignores reality.”
But Biden pumped the brakes Thursday on targeting nuclear facilities.
"They have a right to respond, but they should respond proportionally,” he said.
Biden also weighed in on a potential Israeli strike on Iranian oil. He said Friday that strikes on oil were "under discussion."
"The Israelis have not concluded what they’re going to do in terms of a strike," he said at a briefing. "If I were in their shoes I'd be thinking about other alternatives than striking oil fields."
Taking out Iran's nuclear capabilities could also be difficult since they are spread out, and it could encourage Tehran to build nuclear weapons they have been on the verge of creating for years.
Oil prices jolted amid concerns that Israel could launch such an attack, but while a strike on Iranian oil sites could sow disruption, analysts told Politico that global oil markets have diversified and are more insulated than in the past.
On Friday, Iran's Supreme Leader Ayatollah Ali Khamenei warned in a rare speech Friday that his forces carried out in Tuesday's missile strike a "brilliant" attack that "was the least punishment" for Israel.
Iranian President Masoud Pezeshkian warned earlier this week that Israel will receive a "crushing" response if it oversteps in its retaliation.
Iranian Foreign Minister Abbas Araghchi traveled Friday to Beirut in a show of support for Hezbollah, which is now fending off an Israeli ground incursion.