Plunging squarely into one of the most sensitive issues in the Middle East, Vice President Joseph R. Biden Jr. suggested on Sunday that the United States would not stand in the way of Israeli military action aimed at the Iranian nuclear program.

The United States, Mr. Biden said in an interview broadcast on ABC’s “This Week,” “cannot dictate to another sovereign nation what they can and cannot do.”

"Israel can determine for itself — it’s a sovereign nation — what’s in their interest and what they decide to do relative to Iran and anyone else," he said, in an interview taped in Baghdad at the end of a visit there.

The remarks went beyond at least the spirit of any public utterances by President Barack Obama, who has said that diplomatic efforts to halt Iran’s nuclear program should be given to the end of the year. But the president has also said that he is “not reconciled” to the possibility of Iran possessing a nuclear weapon — a goal Tehran denies.

Mr. Biden’s comments came at a particularly sensitive time, amid the continuing tumult over the disputed Iranian elections, and seemed to risk handing a besieged President Mahmoud Ahmadinejad a new tool with which to fan nationalist sentiments in Iran.

What was not immediately clear was whether Mr. Biden, who has a long-standing reputation for speaking volubly — and sometimes going too far in the heat of the moment — was sending an officially sanctioned message.