Taking sharply different stands, U.S. President Barack Obama urged pressure and diplomacy to prevent Iran from getting a nuclear bomb while Israeli Prime Minister Benjamin Netanyahu emphasized his nation's right to a pre-emptive attack.

Even in proclaiming unity on Monday, the leaders showed no give on competing ways to resolve the crisis. 

Seated together in the Oval Office, Obama and Netanyahu at times tried to speak for each other and sometimes spoke past one another. The two leaders are linked by the history and necessity of their nations' deep alliance, if not much personal warmth, and they both used their moment to try to steer the agenda on their terms. 

"I know that both the prime minister and I prefer to resolve this diplomatically," Obama said. "We understand the costs of any military action." 

If he agreed, Netanyahu said nothing about sanctions or talks with Iran, or Obama's position that there still is time to try to deter Iran peacefully. 

Instead, Netanyahu drew attention back to Obama's acknowledgement that Israel is a sovereign land that can protect itself how it sees fit. 

Israel has 'right to defend itself'

"I believe that's why you appreciate, Mr. President, that Israel must reserve the right to defend itself," Netanyahu said. "And, after all, that's the very purpose of the Jewish state, to restore to the Jewish people control over our destiny," he said.  

Israel, he added, must remain "the master of its fate." 

Across days of comments, speeches and interviews, Obama and Netanyahu left no doubt about where they stand on Iran. Far less clear is whether they have done anything to alter each other's position in what has become a moment of reckoning over Iran, and an important foreign policy issue in the U.S. presidential race. 

Obama's aim is to dissuade Israel from launching what he considers to be a premature and dangerous attack on Iran. 

The leaders spoke to the media at the start of their meeting, not at the end. That left no opportunity for them to reveal how their discussions went, and it reduced the possibility of repeating last year's remarkably blunt scene. 

When they last sat in the Oval Office, in May, Netanyahu lectured Obama in front of reporters as differences over Mideast peace unfolded. 

Telling body language

This time, their body language as they spoke was not so glaring but still telling: Obama addressed the media around the room; Netanyahu spoke directly to Obama and locked on him. 

Netanyahu said later Monday that Obama "understood Israel's position" that it has the right to self-defence. 

Both leaders see a nuclear-armed Iran as a nightmare that could threaten Israel's survival and potentially allow terrorists to grab unthinkably deadly power. Their difference is not over whether force may be needed — Obama has been specific on his willingness to use it — but whether the time for such a drastic step is nearing. 

Israel fears it may soon lose its window to take out Iran's nuclear facilities; Obama sees a longer period for intervention, based on Iran's current nuclear capability and the toll of growing sanctions. He has put increasing emphasis on the political, economic and potential death toll that could come with opening a new Mideast war. 

There are other election-year stakes for Obama. He is under pressure from Republican rivals, and even some Democratic allies, over his backing for Israel. That perception, in turn, can play an important role in swing states such as Florida, where there are many Jewish voters, and in Obama's ability to raise money for his campaign. 

Obama often defends his pro-Israel record and sometimes bristles about being questioned about it. He declared his commitment anew with Netanyahu at his side. 

U.S. 'will always have Israel's back'

"The United States will always have Israel's back when it comes to Israel's security," he said. Netanyahu took it further.  

He said Americans know Israel is their only reliable democratic ally in the Mideast, and that Iran sees the two countries as inseparable enemies. 

"For them, you're the Great Satan, and we're the Little Satan," Netanyahu said. "For them, we are you and you're us. And, you know something, Mr. President — at least on this last point, I think they're right. We are you, and you are us. … Israel and America stand together." 

Iran insists its nuclear program is peaceful, but it has also called for Israel's destruction. 

Although Israel says it hasn't decided whether to strike Iran, it has signalled readiness to do so within the next several months. The United States sees a longer timeline to the moment when a military strike might be appropriate partly based on different views of when Iran would pose an imminent threat. 

With files from CBC News