Amid rising tensions between Jerusalem and Washington regarding setting “red lines” for Iran’s nuclear program, Ambassador to the US Michael Oren made a surprise trip to Israel on Sunday.

During the unplanned visit, Oren participated in consultations with Prime Minister Benjamin Netanyahu ahead of the latter’s trip to New York this week to address the United Nations General Assembly.

The ambassador also briefed Netanyahu before a planned meeting with US Secretary of State Hillary Clinton on Thursday.

Though the US Embassy in Washington called the trip “routine,” few staff members knew that it was taking place. Israeli media outlets jumped on the surprise factor of the 36-hour visit, with Maariv reporting that it was a last-minute effort to bridge the gap between Obama and Netanyahu on the Iran issue.

The Islamic Republic was also the topic of conversation Sunday at a meeting between Clinton and Defense Minister Ehud Barak at the Waldorf Astoria hotel in Manhattan.

Oren acknowledged earlier this month that some of the recent Israeli-American rhetoric had not been helpful. The prime minister had urged the White House to explicitly outline so-called red lines that if crossed would draw the US into a possible military conflict with the Islamic Republic. The Obama administration refused to do so.

In an interview with The Times of Israel, Oren described the “structural differences” between the US and Israel when they grapple with the Iranian danger. Without remotely diminishing what he called the “existential” threat posed by Iran, he noted that Israel faces moments of truth “all the time.”

Netanyahu had requested to meet with Obama on the sidelines of the UN confab, but the White House turned Netanyahu down citing scheduling conflicts. The move drew widespread condemnation from Republicans, including presidential candidate Mitt Romney.

Both Jerusalem and Washington fear that Tehran is pursuing nuclear weapons and agree the regime should be prevented from reaching that goal. The two governments differ regarding the means to achieve this, though. While Netanyahu seems to favor a preemptive military strike some time soon, Obama wants to first exhaust diplomacy and sanctions aimed at convincing Iran to give up on its nuclear ambitions.

Raphael Ahren and David Horovitz contributed to this report.