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President Donald Trump heads to Israel next week where he is poised to make history by becoming the first sitting president to visit the Western Wall — one of the holiest sites in Judaism.

Trump “will say a prayer at the Western Wall,” National Security Adviser H.R. McMaster said Tuesday, who characterized it as a private visit. “No Israeli leaders will join President Trump at the Western Wall.”

National Security Advisor H. R. McMaster speaks during a press briefing at the White House in Washington, DC on May 16, 2017. Olivier Douliery / AFP - Getty Images

McMaster added that Trump, who is also making stops in Saudi Arabia and The Vatican during his first trip abroad as president, is “going to the Western Wall mainly in connection with the theme to connect with three of the world’s great religions.”

“The President's intention is to visit these religious sites to highlight the need for unity among three of the world's great religions,” he said. “Unity in confronting a very grave threat to civilization, and unity in embracing an agenda of tolerance.”

The Western Wall was part of the Second Jewish Temple that was destroyed by the Romans in 70 C.E. For Muslims, it is home to the Dome of the Rock shrine and Al Aqsa mosque which is believed to be the site where the Prophet Muhammad ascended to heaven.

Still, there is a reason why no sitting U.S. president has even visited the site: It was seized from the Jordanians, along with East Jerusalem and the West Bank in 1967, and it’s not officially recognized as Israeli territory.

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George H.W. Bush, Bill Clinton, George W. Bush and Barack Obama all visited the Western Wall as private citizens or as candidates — and never accompanied by an Israeli prime minister.

Also, East Jerusalem is where the Palestinians want to situate the capital of their independent state.

McMaster said that Trump while is in Israel, he will cross over into the West Bank and meet with Palestinian President Mahmoud Abbas in Bethlehem before he heads to Jerusalem to pray at the western wall and visit the nearby Holy Sepulchre church.

Even before Trump sets foot in the Holy Land, he appears to have been tripped-up by his advance team.

The diplomatic dust-up happened, according to Israel’s Channel Two News, when U.S. representatives in Jerusalem turned down a request to have Israeli Prime Minister Benjamin Netanyahu tag along with Trump, saying the president was making a “private” visit to the Western Wall.

They also reportedly spurned an offer from the Israelis to help make the arrangements.

“This isn’t your territory,” one of the reps reportedly told the Israelis. “This is in the West Bank. It is a private visit by the president, and it’s not your business.”

Jews pray at the Western Wall in Jerusalem's Old City on Jan. 17, 2017. Chris McGrath / Getty Images file

After Netanyahu’s office complained, the White House quickly disavowed those remarks.

“They do not reflect the U.S. position, and certainly not the President’s position,” a White House spokesman said.

But neither McMaster nor White House Press Secretary Sean Spicer would be pinned down when asked point blank if the Western Wall is part of Israel. "It's clearly in Jerusalem," Spicer said.

During the campaign, Trump vowed to move the U.S. embassy from Tel Aviv to Jerusalem. But as president he has yet to move forward with that — aware that the move could inflame the Arab world and possibly lead to renewed violence.

For Morton Klein of the Zionist Organization of America, whose group opposes the creation of a Palestinian state, the controversy is just the latest disappointment from the Trump administration.

“We have praised his public stances concerning Israel but he seems to be backtracking at this point on things like moving the (U.S.) embassy from Tel Aviv to Jerusalem,” Klein told NBC News, adding he was also disappointed when Trump invited Abbas to the White House.