Next month, U.S. President Barack Obama and Israeli Prime Minister Benjamin Netanyahu will hold a key meeting over the Iranian nuclear challenge that will test their sometimes rocky relationship. After a weekend visit by National Security Advisor Tom Donilon to Israel, the White House announced this week that Obama will host Netanyahu in Washington on March 5. This will be an opportunity for the two leaders to synchronize their positions on Iran. Whether they can reach some common ground -- now or in the near future -- could be a decisive factor in Israel´s decision-making on whether to strike Iran sometime this year.

International pressure on the Islamic Republic has never been higher. In addition to the new, crippling U.S. sanctions enacted on Dec. 31 and Feb. 6, the European Union recently pledged to halt the importation of Iranian oil by July 1. Iran´s economy is reeling.

For their part, Iranian leaders have struck an increasingly aggressive note. They have threatened a preemptive strike against their foes, and warned that they could close the Strait of Hormuz, through which roughly 20 percent of the world´s traded oil flows daily. In another recent act of defiance, Iranian President Mahmoud Ahmadinejad announced on Feb. 15 that a "new generation" of Iranian centrifuges had just been activated at the Natanz nuclear site. And this week, IAEA inspectors charged with monitoring Iran´s nuclear program were denied access to a military facility, returning to Vienna after what they termed "disappointing" talks with their Iranian interlocutors.

Despite its saber-rattling, Iran is feeling the heat of international sanctions. Over the past month, the Iranian rial has been devalued by 50 percent. Iran has also indicated that it may even be willing to resume diplomacy, which it has scorned since the last round of negotiations in 2009 and 2010.

With the media rife with speculation about a possible Israeli military strike against Iran´s nuclear facilities by this summer, tensions between the two countries have risen to an all-time high. Iran is blaming Israel for the recent assassinations of its nuclear scientists, and Israel is accusing Iran of masterminding the Feb. 13 terror attack against Israeli diplomats in New Delhi, as well as attempted attacks in Tbilisi and Bangkok.

It is no secret that Netanyahu and Obama have never been close, but now is the time for the two leaders to find common ground over the Iranian nuclear issue.

There has already been some progress in getting top U.S. and Israeli officials to speak about Iran in similar terms. Last week in the Knesset, Netanyahu said it is critical that the world -- not just Israel -- identify "red lines" when dealing with the Iranian nuclear program. In a CBS appearance last month, Defense Secretary Leon Panetta declared that Iran´s development of a nuclear weapon, as well as closure of the Strait of Hormuz, are "red lines" for the United States.

However, the United States and Israel clearly differ in where their red lines lie. The United States has put the focus on Iran actually gaining a nuclear weapon, while Israel -- more vulnerable to Iranian missiles due to its geographic proximity -- views the threshold as the Iranian regime´s acquisition of enough low-enriched uranium to build a bomb, pending a political decision to convert it to weapons- grade fuel.

The other set of differences between the United States and Israel has to do with how long they are willing to wait before judging the international sanctions of Iran to be a success or failure. On the one hand, this is the first time that the United States and the EU have imposed the type of "crippling" sanctions that Israel has long called for. But on the other, recent statements by Israeli Defense Minister Ehud Barak signal that Israel believes its window for military action is rapidly closing. As a result, Israeli officials fear they might not have the time to wait and see whether the sanctions halt Iran´s nuclear program peacefully.

Israeli military capabilities to strike Iran´s proliferating nuclear sites -- especially those bunkered deep within a mountain outside the city of Qom -- are more limited than those of the United States. The prospect of a new round of Iranian-U.S. diplomacy is another critical component of this equation, as it could further postpone U.S. military action in the event that sanctions fail. Taken together, these circumstances could force an Israeli decision on a preemptive strike under suboptimal conditions.

All this puts Israel on the horns of a dilemma. It can hope that sanctions will ultimately deter Iran´s nuclear program, but this may mean foregoing decisive action against what it sees as an existential threat in the hope that the United States will act further down the road. Barak and Netanyahu are commonly identified as favoring a strike, but based on my recent trip to the region, it is clear that others within the Israeli cabinet and defense establishment still have doubts. As such, the prospect of a strike is not inevitable. If Israel believed that the United States were absolutely committed to handling this issue, it would certainly shift the Israeli debate about whether to strike.

But without absolute certainty, holding off on a strike is a tough decision for Israeli officials to make. Many Israeli military leaders are children of Holocaust survivors who joined the Israeli army to ensure Israeli self-reliance in fighting against enemies who regularly pledge to eradicate it. A poignant reminder is the iconic photo of Israeli jets flying over Auschwitz in 2003, which hangs on the walls of many of their offices.

Nonetheless, it is a fundamental misreading of Israel to view this as an ideological issue. Israeli considerations of a strike are rooted not in their ethos of self-reliance, but in the fear that the United States will ultimately fail to strike, even if sanctions fail. Israeli officials´ fears are compounded by their knowledge that the American people are fatigued by conflict, and by the suspicions of some that the United States has not entirely ruled out a strategy of containment, U.S. protestations to the contrary.

The Obama administration´s official policy opposes containment, holding that the Iranian nuclear program is too destabilizing for the Middle East. As the president told NBC on Feb. 5, "We are going to do everything we can to keep Iran from getting a nuclear weapon, and creating an arms race -- a nuclear arms race -- in a volatile region." Concerns about Iran handing dirty bomb technology to non- state actors, such as the Lebanese militia Hezbollah, along with fears that Iran would seek to dominate the Persian Gulf, are also all too real.

In light of these threats, some analysts could argue that Obama -- who is known for his preference for Predator drone strikes in Pakistan and such surgical operations as the one that killed Osama bin Laden -- would indeed resort to military action if sanctions failed. And despite tensions between Obama and Netanyahu over the Middle East peace process, sources close to Obama argued to me that these policy differences in no way infringe upon the president´s commitment to Israel´s security.

At the same time, U.S. officials have also raised fears of an Israeli strike in the short term -- as evidenced by Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey´s comments on Feb. 19 that an Israeli attack would be "destabilizing." Their fears center on the belief that an attack by Israel could unravel international sanctions, and that Iran would be able to reconstitute its program in fairly short order.

How can Obama and Netanyahu win each other´s trust? The two sides should come to a more precise understanding of U.S. thresholds for the Iranian nuclear program and American responses should they be breached, as well as an agreement on a timetable for giving up on sanctions so their Iran clocks are synchronized. In other words, the two sides need to agree on red lines that might trigger action. Israel will probably seek some guarantees from the United States before agreeing to forgo a pre-emptive strike that might not succeed.

It may turn out that such guarantees are impossible, given the mistrust between the two parties and the ever-changing regional circumstances. Whatever the mechanism, there is no doubt that the U.S.-Israel relationship could benefit greatly from a common approach toward the Iran nuclear program at this tumultuous time. Their upcoming meeting and the months ahead promise to test the Obama- Netanyahu relationship like never before.