In the U.S.-Israel dispute over Iran's nuclear program, Nobel laureate and Holocaust survivor Elie Wiesel has emerged as an unlikely protagonist -- siding with Israeli Prime Minister Benjamin Netanyahu rather than President Obama.

In his joint address to Congress, Netanyahu made a point of recognizing the 86-year old Wiesel, who sat in the Speaker's Box with the prime minister's wife, Sara. After warning lawmakers that "standing up to Iran is not easy," Netanyahu sparked loud applause by saying, "Standing up to dark and murderous regimes never is. With us today is Holocaust survivor and Nobel Prize winner Elie Wiesel."

"Elie, your life and work inspires to give meaning to the words, 'never again,'" he added, as lawmakers gave Wiesel a standing ovation. "And I wish I could promise you, Elie, that the lessons of history have been learned. I can only urge the leaders of the world not to repeat the mistakes of the past."

"But I can guarantee you this, the days when the Jewish people remained passive in the face of genocidal enemies, those days are over," Netanyahu concluded, emphatically.

Wiesel, a personal friend of Obama's, has been an outspoken critic of a possible nuclear deal with Iran since 2013. Rabbi Shmuley Boteach, executive director of the advocacy group This World: The Values Network, has collaborated with Wiesel in the past and urged him to come to Washington and attend the prime minister's speech.

"Of course it wasn't an easy decision for Professor Wiesel," said Boteach, who has known the Nobel Peace Prize winner for 26 years. "He has deep affection for the president. But he doesn’t feel saying the Jewish people face danger is offensive to the president."

While Obama first heard Wiesel as a college student, they got to know each other during a 2009 memorial at the Buchenwald concentration camp where the president gave him the last word. They have dined together on occasion, and Wiesel told Israel's Haaretz newspaper more than two years ago that the two planned to collaborate on a book after the 2012 election.

During his time in Washington this week, Wiesel spoke on the issue with Sen. Ted Cruz (R-Tex.) and Rep. Brad Sherman (D-Calif.) during a panel Monday on Capitol Hill. He headed back to New York City shortly after talking with Netanyahu following Tuesday's speech.

According to the office of House Speaker John A. Boehner (R-Ohio), the decision to invite Mr. Wiesel was "an easy and mutual one made by the speaker and the prime minister’s office."