WASHINGTON (AP) -- After a combative start to his presidency, Donald Trump delivered a more unifying message Sunday and sought to reassure Americans he was up to the daunting task ahead, as he turned to the business of government.
Speaking in the White House East Room during a swearing-in ceremony for top aides, the president warned his staff of future challenges but declared he believed they were ready.
"But with the faith in each other and the faith in God, we will get the job done," the president said. "We will prove worthy of this moment in history. And I think it may very well be a great moment in history."
Trump's reassurance came after a day marked by global protests against his presidency and his own complaints about media coverage of his inauguration. He said his staff was in the White House not to "help ourselves" but to "devote ourselves to the national good."
Trump held up the letter left to him by his predecessor, Barack Obama -- a White House tradition. "It was really very nice of him to do that," Trump said. "We will cherish that." He said the contents will remain private.
Earlier Sunday, Trump offered a scattershot response to the sweeping post-inauguration protests a day earlier, sarcastically denigrating the public opposition and then defending demonstrators' rights a short time later.
"Watched protests yesterday but was under the impression that we just had an election! Why didn't these people vote? Celebs hurt cause badly," Trump tweeted early Sunday morning. Ninety-five minutes later, he struck a more conciliatory tone.
"Peaceful protests are a hallmark of our democracy. Even if I don't always agree, I recognize the rights of people to express their views," the president tweeted, still using his personal account.
The dueling tweets marked his administration's first response to the more than 1 million people who rallied at women's marches in Washington and cities across the world. Hundreds of protesters lined the street as Trump's motorcade drove past on Saturday afternoon, with many screaming and chanting.
The Washington rally appeared to attract more people than attended Trump's inauguration on Friday, but there were no completely comparable numbers. Regional transportation officials tweeted on Sunday that 1,001,616 trips were taken on the rail system on Saturday. Metro spokesman Dan Stessel had said that on Friday, the day of Donald Trump's inauguration, just over 570,000 trips were taken on the rail system.
Even suggestions of weak enthusiasm for his inauguration clearly irked the new president, and appeared to knock the White House off its footing as it took its earliest steps.
On Sunday, Trump's spoke with Israeli Prime Minister Benjamin Netanyahu, who accepted an invitation to visit the White House in early February. The prime minister is hoping to forge a "common vision" with the newly inaugurated U.S. president that could include expanded settlement construction and a tougher policy toward Iran.
Trump also announced that he's set up meetings with the prime minister of Canada, Justin Trudeau, and Mexican President Enrique Pea Nieto.
"We're going to start some negotiations having to do with NAFTA," he said of his meeting with Mexico, along with immigration and security at the border. Trump has promised to build a wall along the length of the southern border and insisted that Mexico will pay for it.
Trump had no plans to sign any executive orders on Sunday. But his chief of staff, Reince Priebus, said on "Fox News Sunday" the president would spend his first full week in office undoing some of his predecessor's agenda and planned to sign executive orders on immigration and trade.
Trump has pledged to scuttle trade deals such as a pending Asia-Pacific agreement and overturn Obama's executive order deferring deportations for 700,000 people who were brought into the country illegally as minors.
Trump plans to meet Monday with a bipartisan group congressional leaders to discuss his agenda.
Later in the week, he'll address congressional Republicans at their retreat in Philadelphia and meet with British Prime Minister Theresa May.
In talk show interviews Sunday, Trump's advisers defended his criticism of journalists for correctly reporting that his inauguration drew a smaller crowd President Barack Obama did eight years ago, saying the Trump administration was supplying "alternative facts."
"There's no way to really quantify crowds. We all know that. You can laugh at me all you want," Kellyanne Conway told NBC's "Meet The Press." She added: "I think it's actually symbolic of the way we're treated by the press."
Aides also made clear that Trump will not release his tax returns now that he's taken office, breaking with a decades-long tradition of transparency. Every president since 1976 has released the information, but Trump has said he doesn't believe Americans care whether he follows suit.
Throughout the campaign, Trump refused to make his filings public, saying they're under audit by the Internal Revenue Service and he'd release them only once that review is complete. Tax experts and IRS Commissioner John Koskinen said such audits don't bar taxpayers from releasing returns.
"He's not going to release his tax returns. We litigated this all through the election. People didn't care," Conway said on ABC's "This Week."
Trump, whose 12th wedding anniversary was Sunday, also attended a reception for law enforcement officers and first responders who helped with his inauguration. He singled out the work of FBI Director James Comey, whom he offered a handshake and hug.