Donald Trump was “exhausted” during his first trip overseas as President and asked his daughter to attend a scheduled event in his place.
Ivanka Trump spoke at the “tweeps” youth forum in Riyadh, an event to discuss combating extremism on social media, instead of her father after a long day for the President of meetings, conferences and speeches.
Mr Trump abruptly skipped the event on the second day of his trip in Saudi Arabia and the day before he was due to meet with Israeli leaders to negotiate a peace process with Palestine.
A White House official was asked by reporters why Mr Trump had deviated from his prepared speech earlier that day to Muslim leaders about fighting Islamist terrorism.
“Just an exhausted guy,” she replied.
On the stage of the youth forum in the evening, Fox News anchor Bret Baier announced that the President would not attend the event, but there would be a "surprise guest" - his daughter.
Ms Trump gave a three-minute speech in his place, thanking the Saudi royals for their hospitality.
"Social media is an incredibly powerful tool which empowers the people," she said.
It was the second time in a week that the 35-year-old had stepped in to replace the President, after leading a White House meeting on human trafficking with members of Congress while her father was giving a commencement address for the US Coast Guard Academy.
Over the weekend, Mr Trump received the highest civilian honour in Saudi Arabia and bowed while he received it. His daughter and wife, Ivanka and Melania Trump, did not wear headscarves during the trip. He previously attacked former President Barack Obama for similar displays.
He also attacked his former rival for the White House, Hillary Clinton, for her "lack of stamina" when footage captured her being assisted into a car after a lengthy 9/11 memorial ceremony during a hot day in New York.
He has not faced criticism for his own exhaustion three days into the first overseas trip since his Inauguration.
During the weekend, the President signed a $109.7 billion arms deal with Saudi Arabia, pledged to visit Egyptian President Abdel Fattah al-Sisi and gave a speech on combating terrorism.
In his anticipated speech, he urged nations to engage in a fight between “good and evil”, and to “drive them [terrorists] out”, but also expressed hope that his speech could be the start of peace in the Middle East.
In an unexpected turn, he criticised the “reckless pursuit of conflict and terror” by Iran’s government, which victimised its own people and supported Bashar al-Assad in carrying out “unspeakable crimes” in Syria.
Mr Trump did not mention Saudi atrocities in Yemen, or the US’s potential ties with Russia, who also carried out deadly air strikes in Syria.
Before he flew to the Middle East last week, Mr Trump fired former FBI director James Comey under the pretence that he was a “showboat”. Mr Comey had been leading up an investigation into potential ties between Mr Trump and his team with the Russians before and after the election.