Speaking at the United Nations on Sept. 27, Israeli Prime Minister Benjamin Netanyahu used a red marker to graphically sharpen the focus on the need for a "red line" in halting the Iranian nuclear program.

The issue of red lines is being conflated by some with the idea of delivering a public ultimatum to Iran. But that's not quite right: Setting red lines is not about what is said publicly, but rather about what Tehran views as credible -- however it is conveyed.

There are signs that Netanyahu and U.S. President Barack Obama, since their recent hour-long phone call, are renewing their efforts to reach a quiet understanding on this critical issue. In their speeches at the United Nations this past week, both leaders kept the focus on Iran -- even while stepping back from a U.S.-Israeli confrontation.

This was particularly evident in Netanyahu's speech, where the Israeli premier no longer made it sound like an Israeli strike was imminent before the U.S. presidential election in November, and subtly shifted the parameters of the debate from Israel's closing window of action (what Israeli officials describe as the "zone of immunity") to the point where can Iran make an easy dash to weapons-grade nuclear fuel.

Netanyahu also said the United States and Israel are currently "in talks" on the Iran issue, suggesting the two countries are focused on how to best ensure and measure the shared objective of preventing the Islamic Republic from going nuclear. However, there is no denying that tensions still exist between the two allies. Their war of words reached a high pitch recently when Netanyahu, responding to what he interpreted as a personal rebuke by the chairman of the U.S. Joint Chiefs of Staff, declared that if the United States does not put down red lines in halting the Iranian nuclear program, it has no moral right to put a red light in front of an Israeli strike. In a 60 Minutes interview, Obama appeared to dismiss such public statements as "noise."

It's time to dial down the rhetoric. In truth, both sides could use a dose of humility before sounding off in public.

For Israel, humility is required because public confrontation with the United States does not make any strategic sense. Israeli security officials will be the first to say there is no substitute for policy intimacy with their patron in Washington. Moreover, when there is a public disagreement with the United States on the issue of the nuclear program, only Iran profits. Tehran is bound to interpret such divisions as a lack of resolve.

But we in the United States could also use some humility. First, let's admit that our track record in halting rogue nuclear programs is rather poor. We may have bought off Libya, but we did not stop the nuclear programs of North Korea and Pakistan. As has been said by the former deputy head of the Israeli Atomic Energy Agency Ariel Levite, now at the Carnegie Endowment, the U.S. approach has been "too early, too early, oops, too late."

Second, Israel has strong historical reasons to be skeptical of international guarantees. On the eve of the epic 1967 war, Israel's then Foreign Minister Abba Eban came to the White House to remind President Lyndon Johnson of the U.S. commitment to militarily intercede if Egypt closed a key waterway -- the Straits of Tiran -- to Israeli shipping. But the United States was preoccupied with Vietnam and other issues, and Israel was left on its own. This traumatic moment enshrined Israel's ethos of self-reliance.

Third, we need to admit that there are legitimate questions whether the United States will be able to detect with confidence Iran's dash to weaponization. In his U.N. remarks, Netanyahu alluded to Iran's ability to reach a level of enrichment by next summer that would put it in easy reach of weapons-grade nuclear fuel in as little as one to two months. If the Islamic Republic takes that step, will Washington discover it quickly enough to do something about it?

Iran allows video cameras to film around the clock in its underground sites, but it only allows the International Atomic Energy Agency (IAEA) inspectors to collect the images every six to eight weeks. Therefore, a cancelled IAEA visit can become a full-blown crisis: It would mean the world has no way of knowing whether Iran is expanding its enrichment efforts to produce weapons-grade uranium. Furthermore, it remains possible that Iran could install the next generation of centrifuges, allowing it to produce highly enriched uranium even quicker. The fact is, by sometime after the summer of 2013, we simply may not know what Iran is capable of.

Fourth, even if the United States is successful in detection, will Washington act on that knowledge in timely fashion?

According to an op-ed by former CIA chief Michael Hayden, even when the United States confirmed that Syria was building a nuclear reactor in 2007 and that it had a military purpose, the intelligence community did not recommend military action because it could not find the reprocessing plant needed for weaponization. In his memoir, President George W. Bush also cited this as the reason for the lack of U.S. action.

Moreover, top officials like Defense Secretary Robert Gates were preoccupied with other initiatives such as the surge in Iraq, and Secretary of State Condoleezza Rice was focused on the talks with North Korea. As a result, Israel acted alone -- and the reactor was destroyed. While there are more differences than similarities with the Iranian case, the episode in Syria was yet another instructive example for Israel that its superpower ally is sometimes busy elsewhere.

Finally, it is worth stating the obvious: Israel is threatened by the Iranian leadership with "full annihilation," in the words of armed forces chief of staff Major General Hassan Firouzabadi, and routinely called a cancerous tumor that needs to be removed. As such, it perceives its margin of error as narrower than a superpower with global interests resting safely an ocean away.

Of course, all sides hope that the nuclear standoff with Iran will be resolved peacefully with a mix of diplomacy and sanctions. Yet, what if this mix does not work? With the stakes so high, it is important that both Obama and his Republican challenger Mitt Romney spell out in detail to the American public how the United States will prevent Iran from acquiring a nuclear weapon. Given our track record, it would be good to start with humility.