President Barack Obama and Israeli Prime Minister Benjamin Netanyahu have one important thing in common, and that is their belief in Israel’s right to exist. However, they seem to differ on how Israel should maintain that existence, particularly in relationship to the nuclear threat posed by Iran.

Some of these differences were aired Monday during their meeting at the White House. Obama insisted there’s “still a window that allows for a diplomatic solution” to the Iranian threat, while Netanyahu stressed Israel’s “sovereign rights…and the right to act unilaterally” to defend itself.

According to reports, the two-hour long meeting was far more cordial than their last one, during which Netanyahu attempted to take Obama to task, lecturing him on Israel’s history and its ties to the United States.

Despite their differences, Obama maintained that the United States has “Israel’s back,” a statement that resonated from his appearance at the American Israel Public Affairs Committee on Sunday.

“As I indicated yesterday in my speech, when I say all options are on the table, I mean it,” Obama said.

A critical option facing the United States is what happens if Israel acts unilaterally and initiates a pre-emptive strike on Iran’s nuclear facilities, as they did with surgical precision in 1981 on a reactor in Iraq and 2007 on a reactor in Syria?

“My supreme responsibility as prime minister of Israel,” Netanyahu told the president, “is to ensure that Israel remains the master of its fate.”

If the United States truly has Israel’s back, then they would out of necessity be drawn into the conflict, which is one reason Obama is trying his best to tamp down the “loose talk” about a possible war.

For Netanyahu and Israel, the clock is ticking, and they feel the longer they wait, it gives Iran–which has called for the annihilation of Israel–more time to enhance its uranium enrichment program and stabilize its nuclear capability.

“I reserve all options, and my policy is not going to be one of containment,” Obama said. “My policy is prevention of Iran obtaining nuclear weapons.”

Economic sanctions are one option Obama has discussed, but that would have to be bolstered by the European Union, especially as it pertains to the distribution of oil.

In a related matter, the BBC reported that Iran is prepared under certain conditions to grant inspectors from the U.N.’s International Atomic Energy Agency access to the key military site of Parchin.

Curiously, while Iran has signed the Treaty on the Non-Proliferation of Nuclear Weapons, Israel has not.