Vice-President Joe Biden told ABC's This Week on Sunday that the US wouldn't stand in the way of Israel if they decided Iran was an existential threat.Speaking to host George Stephanopoulos from Camp Victory in Iraq, Biden told ABC that "we cannot dictate to another soveriegn nation … if they make the decision they are existentially threatened."Asked by Stephanopoulos about Israeli Prime Minister Benjamin Netanyahu's assertion that he will give international peace efforts with Iran only until the end of the year to work, Biden insisted the US would not second-guess any decisions Israel makes regarding Iran."Israel can determine for itself - it's a sovereign nation - what's in their interest, and what they do with Iran or anything else," said Biden.Asked if the US would stand in the way of an Israeli attack on Iran's nuclear facilities, Biden evaded the question.