Netanyahu, who has made clear that Israel is operating on a shorter timeline than the United States, warmly welcomed expressions of U.S. resolve against Iran but also declared that Israel was entitled to defend itself, by itself.

While the United States and Washington share a commitment to prevent Iran from becoming nuclear-armed, Israel sees a threat to its existence from Tehran atomic program, which Iranian officials say has only peaceful purposes.

We do believe there is still a window that allows for a diplomatic resolution to this issue, Obama said.

Even though Obama has ratcheted up his tone against Iran in recent days, he and Netanyahu went into the talks divided over how quickly the clock is ticking toward possible military action. The meeting appeared unlikely to change that.

In private, the leaders made no concrete decisions but looked at both the price of taking action against Iran - which could spike oil prices and sow global economic upheaval - and the consequences of inaction, which could lead to a nuclear arms race in the Middle East.

They remain far apart on any explicit nuclear red lines that Iran must not be allowed to cross, and officials on both sides said the question was not even raised in the White House talks.

Despite that, the body language between the two leaders was a stark contrast to their last Oval Office meeting in May 2011 when Netanyahu lectured Obama on Jewish history and criticized his approach to Israeli-Palestinian peacemaking.

This time, Obama and Netanyahu appeared businesslike but cordial as they sat side-by-side, chatting amiably as reporters entered the room and sometimes nodding when the other spoke.

Obama's encounter with Netanyahu was considered crucial to preserving the trust of America's closest Middle East ally, which fears that time is running out for an effective Israeli strike on Iran, and to counter election-year criticism from Republican rivals who question his support for the Jewish state.

He is also trying to tamp down increasingly strident talk of another war in the region, which could have damaging repercussions for the fragile U.S. economic recovery - a consequence that could threaten his re-election chances.

Speculation has mounted that Israel could opt to act militarily on its own unless it receives credible guarantees that the United States will be ready to use force against Iran if international sanctions and diplomacy fail.

Israel, believed to be the only nuclear weapons power in the Middle East, fears Iranian nuclear facilities may soon be buried so deep that they would be invulnerable to its bunker-busting bombs, which are less powerful than those in the U.S. arsenal.

Israel insists that military action against Iran would be warranted to prevent it from reaching nuclear weapons capability, as opposed to when it actually builds a device. Washington has not embraced that idea.

U.S. officials say that while Iran may be maneuvering to keep its options open, there is no clear intelligence that the country has made a final decision to pursue a nuclear weapon.

Mitch McConnell, the U.S. Senate's top Republican, told the AIPAC meeting he would propose that Congress authorize the use of force against Iran if the U.S. intelligence community finds that Iran is enriching uranium to weapons grade levels or has decided to develop a nuclear bomb.

Obama said both he and Netanyahu prefer to resolve this diplomatically and also understand the cost of military action.

Netanyahu did not echo that sentiment, saying instead that Israel and America stand together.

After talks with Obama and his aides and lunch with the president, Netanyahu told reporters, They understood Israel's position that it has a right to defend himself.

Shayne Heffernan

Shayne Heffernan oversees the management of funds for institutions and high net worth individuals.

Shayne Heffernan holds a Ph.D. in Economics and brings with him over 25 years of trading experience in Asia and hands on experience in Venture Capital, he has been involved in several start ups that have seen market capitalization over $500m and 1 that reach a peak market cap of $15b. He has managed and overseen start ups in Mining, Shipping, Technology and Financial Services.