When President Obama meets with Benjamin Netanyahu today, one of his goals will be to assure the Israeli prime minister that the United States will use force to delay Iran’s nuclear program if the current round of sanctions doesn’t work. All the while, Netanyahu’s objective will be to avoid having to make a direct commitment to the president not to order his jets to bomb Iran’s nuclear infrastructure.

Three months ago, speaking at the memorial to Israel’s founding father, David Ben-Gurion, Prime Minister Netanyahu gave a speech many Israeli observers considered a window into his own thinking on Iran. In it he described how the vote of Ben-Gurion’s cabinet to declare statehood was very close, with only six in favor and four voting against. Netanyahu asked his audience to imagine if one of the yes votes went the other way.

“He understood full well the decision carried a heavy price, but he believed not making that decision had a heavier price,” Netanyahu said of Israel’s founding father. “We are all here today because Ben-Gurion made the right decision at the right moment.”

The speech made headlines in Israel because it came only a few days after comments from Defense Secretary Leon Panetta suggesting an Israeli strike on Iran would be disastrous. Just as Ben-Gurion had chosen to declare independence over the counsel of his allies, Netanyahu’s message was that he too may have to go against Israel’s most valued ally in the world today. 

Giora Eiland, once a national security adviser to former Prime Minister Ariel Sharon, said Netanyahu prefers to “compare himself to the first prime minister in Israel who is known for his courageous decisions and for his determination and for his ability to decide despite the decisions of everyone else.”

At issue is that the United States and Israel disagree on what the trigger or “red line” should be for striking Iran’s nuclear program. The Israelis seek to destroy Iran’s ability to manufacture an atomic weapon, whereas President Obama has pledged only to stop Iran from making a weapon.

“The technical assessments are very similar,” Ephraim Asculai, an Israeli nuclear scientist who worked for 40 years at the Israel Atomic Energy Commission, told The Daily Beast last week. “The discrepancies come at the definition of red lines, or the definition of the time when something must be done is considered.”

Asculai added, “The United States does not think the time has come when it must make a decision and must take severe action. There lies the big difference between the United States and Israel; Israel thinks the time is here.”

This underlying difference between Israel and the U.S. was apparent in Obama’s speech Sunday before the American Israel Public Affairs Committee. The president repeated his promise to stop Iran from obtaining a nuclear weapon and said the military had prepared plans for such a contingency. But Obama also decried “too much loose talk of war.” And while he acknowledged Israel’s right to defend itself, he also said, “now is not the time for bluster; now is the time to let our increased pressure sink in, and to sustain the broad international coalition that we have built.”

This disagreement between allies has been brewing for nearly a year. As Newsweek reported last month, Israel stopped sharing key military planning data on Iran with the United States last summer. And while the exchanges have resumed, Israel is still keeping a “top layer” of data to itself.

Eiland told The Daily Beast that Obama had the ability to call off an Israeli attack if he sought an explicit promise from Netanyahu not to do it. “The real concern is what might happen if the president said in explicit terms something like ‘don’t do it,’ or ‘promise you won’t do it,’ and will insist on such a guarantee,” Eiland said. “I am not sure this scenario will occur. But if it happens, and if the president is determined to convey such a clear message and will leave no room for any possible interpretation, then I think no matter what Bibi really wants, it will be almost impossible to make a decision in absolute contradiction to the president’s wishes.”

Israeli prime ministers on two occasions—Iraq and in Syria—have attacked nuclear programs without the explicit permission of the United States. Israeli prime ministers also have disobeyed explicit requests from U.S. presidents on other issues such as the Israeli decision to leave troops inside Palestinian cities in 2002 during Operation Defensive Shield.

The real concern is what might happen if the president said in explicit terms something like ‘don’t do it,’ or ‘promise you won’t do it.’

“In these examples, we could always say to ourselves and the Israeli public—at the end of the day it’s our security interest and with all due respect, it is less important to America what is happening, but it’s crucially important to us,” Eiland said.

But Eiland added that in the case of Iran, it’s different. “The Iranian case is different because the American vital interest might be affected,” Eiland said. “To do something against an American explicit request is much different. Besides the operational risks that are very high and the general security risks. We are taking a real political risk that no Israeli prime minister can take.” Eiland said, however, that such a risk would be present only “as long as the American ‘no’ is as explicit as I described.”