Israel has asked the United States for weapons like the Massive Ordnance Penetrator in the past and has been turned down. American officials declined to say whether the yearlong negotiations with Israel that resulted in the new arms package had included a discussion of the new bomb.

Instead, they pointed to a decision by President Obama to send advanced refueling tanker planes to Israel that would make it possible for the country’s fighter aircraft to reach as far as Iran. A similar refueling capability was turned down during the administration of President George W. Bush.

George Little, the Pentagon press secretary, said the arms package to Israel was “unprecedented” and would “guarantee and augment our strong ally’s qualitative military edge for a generation to come.”

The debate is about more than just equipment. Israel’s position has been that Iran cannot be allowed to build up too large a stockpile of medium-enriched uranium that could allow it to then race for a bomb. When Mr. Netanyahu addressed the United Nations in New York last September, he drew a red line across a cartoon picture of a bomb, which aides later said indicated that Iran would not be allowed to amass enough medium-enriched uranium to get enough fuel to make a single weapon.

But most of Iran’s production of that uranium is occurring inside the mountain at Fordo. So far, Iran has stayed just below Mr. Netanyahu’s red line, converting some of the fuel to a metallic form that can be used in a nuclear reactor — but that would take significantly more time to further enrich it to bomb-grade material. To the United States, this has offered up more time for a diplomatic solution. To many Israeli officials, it is a ploy, intended to buy time as Iran installs a new generation of centrifuges that could speed its production.

“It’s all about timetables,” said Dore Gold, the president of the Jerusalem Center for Public Affairs and a member of Mr. Netanyahu’s inner circle of strategists. “If you say the goal is to halt Iran in the enrichment phase, you don’t have much time. If you are waiting for Iran to weaponize” — the position the Obama administration has taken — “maybe you can give it another year or more.”

Mr. Yaalon suggested that there was still time. “There are other tools to be used and to be exhausted, whether it is diplomacy, economic sanctions,” he said.