STORY: Speaking in an interview with Israel's Channel 12 TV that was recorded before he left Washington on Tuesday and aired on Wednesday, Biden said he would keep Iran's powerful Islamic Revolutionary Guard Corps (IRGC) on the U.S. Foreign Terrorist Organizations (FTO) list even if that killed off the 2015 Iran nuclear deal.
Tehran struck a deal with six major powers in 2015 under which it limited its nuclear program to make it harder to obtain a weapon in return for relief from economic sanctions.
U.S. President Donald Trump reneged on the deal in 2018 and reimposed harsh sanctions on Iran, prompting Tehran to start violating the agreement's nuclear limits about a year later.
In the interview, Biden called Trump's move a "gigantic mistake", noting that the country is "closer to a nuclear weapon now than they were before."
Efforts to resurrect the deal so far failed, with a senior U.S. official telling Reuters that chances of its revival were lower after indirect talks between the United States and Iran in Doha two weeks ago.
Asked if he would use force against Iran to prevent Tehran from obtaining a nuclear weapon, Biden replied: "If that was the last resort, yes."
Iran denies it seeks nuclear weapons, saying that its nuclear program is for solely peaceful purposes.
Negotiators appeared close to a new deal in March, but talks broke down largely because of U.S. refusal of Tehran's demand that Washington remove the IRGC from the terrorism list, arguing this was outside the scope of reviving the pact.