WASHINGTON — Taking sharply different stands, President Barack Obama on Monday 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, neither leader gave ground on how to resolve the crisis.

Seated together in the Oval Office, Obama and Netanyahu at times tried to speak for each other, and other times spoke past one another. The president and prime minister are linked by the history and necessity of their nations’ deep alliance, if not much personal warmth, and both sought to steer the Iran 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.

“I believe that’s why you appreciate, Mr. President, that Israel must reserve the right to defend itself,” Netanyahu said.

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

Israel has not yet decided whether to launch a unilateral strike on Iran, a point underscored in the White House meetings.

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.

Both are adamant Iran must not develop a nuclear bomb. Obama’s aim is to keep Israel from launching an attack on Iran’s nuclear facilities, fearing that would do little lasting good toward the goal and engulf the region and the United States in another war.