President Donald Trump threatened Thursday to withhold aid money from the Palestinians until they return to peace talks with Israel as he sat down with Israeli Prime Minister Benjamin Netanyahu on the sidelines of an economic summit in Switzerland.

Trump's decision last year to recognize Jerusalem as Israel's capital roiled Arab nations and led the Palestinians to refuse to meet with Vice-President Mike Pence during his visit to the Mideast this week. They also declared a new U.S.-led peace push dead, saying Washington can no longer be trusted as an honest broker.

Trump said that decision has consequences. The U.S., he said, gives "hundreds of millions of dollars in aid and support" to the Palestinians, and "that money is on the table and that money's not going to them unless they sit down and negotiate peace."

The Palestinian envoy to Washington, Husam Zomlot, accused the president of "backstabbing" the Palestinians. In a speech at the Washington-based Middle East Institute, Zomlot said Trump had reneged on his promise not to prejudge solutions to the conflict and chided the president for acting "triumphant" and "victorious" in Davos.

"We don't understand, triumphant and victorious, what is it? For killing the only possible solution? For pushing us to the Armageddon?" Zomlot said.

President in Davos

Trump's comments came shortly after he arrived at the World Economic Forum, which brings together world leaders, business executives and celebrities. His appearance is aimed at luring foreign investment to the U.S. and highlighting his "America first" economic agenda, despite its seeming odds with a gathering that celebrates global co-operation and free trade.

Washington has contributed over $5 billion in economic and security aid to the Palestinians since the mid-1990s. Annual economic aid since 2008 has averaged around $400 million, much of it devoted to development projects.

State Department spokeswoman Heather Nauert said all bilateral assistance to the Palestinians, including economic security aide, is at risk if the Palestinians don't come to the negotiating table.

Trump met with Israeli Prime Minister Benjamin Netanyahu at the World Economic Forum in Davos. (Evan Vucci/Associated Press)

Last week, the Trump administration moved to withhold some — but not all — of a scheduled aid payment to the United Nations agency that assists Palestinian refugees. The Trump administration said it would provide $60 million, while keeping $65 million until the UN body undertakes a "fundamental re-examination." Nauert said that action is unrelated.

Israel has been overjoyed by Trump's pivot on Jerusalem, which Netanyahu hailed Thursday as an "historic decision that will be forever etched in the hearts of our people."

During his visit to Israel this week, Pence told Israeli lawmakers that the U.S. was fast-tracking the embassy plans, aiming to move it from Tel Aviv to Jerusalem by the end of 2019. Trump said he anticipates having "a small version" of the embassy open sometime next year.

In his remarks, Trump referenced Pence's trip to the Middle East, which did not include a meeting with Palestinian leaders. Trump said: "They disrespected us a week ago by not allowing our great vice-president to see them," adding: "Respect has to be shown to the U.S., or we're just not going any further."

Palestinians burned a poster of U.S. Vice-President Mike Pence earlier this month during a protest against Pence's visit to Israel, in the West Bank city of Bethlehem. (Mussa Qawasma/Reuters)

Trump arrived in Zurich ahead of schedule and immediately boarded a U.S. helicopter for the flight to Davos, where the World Economic Forum is being held. The approximately 40-minute trip took Trump over a snowy countryside dotted with houses, frosted mountains and a glistening lake.

As Trump got off the helicopter in Davos, he gestured to aides who held him by the arms as he walked across the snowy landing zone to his waiting car.

"This will be a very exciting two days," Trump said as he arrived at the summit site, adding that he was bringing a message of "peace and prosperity" to the gathering.

'Tremendous investment'

Hours later, he said his visit had already been "very successful," telling reporters between meetings that "we are seeing tremendous investment and today has been a very exciting day, a very great day and great for our country."

While the president is expected to declare that the United States is open for business, the protectionist-leaning president's attendance at the annual gathering for free-trade-loving political and business elites has raised eyebrows. His decision to sign new tariffs boosting American manufacturers this week has prompted fresh concerns about his nationalist tendencies.

But Trump said there was nothing contradictory about his visit.

"When I decided to come to Davos, I didn't think in terms of elitist or globalist, I thought in terms of lots people that want to invest lots of money and they're all coming back to the United States," he said in an interview with CNBC.

"After I said that I was going, there were massive stories about 'the elite' and 'the globalists' and the planes flying in and everything else. It's not about that," he added.

Trump also seemed eager to dispel concerns about his global leadership.

During a meeting with British Prime Minister Theresa May, Trump insisted the U.S.-U.K. relationship isn't strained.

"We're on the same wavelength in I think every respect," Trump said, stressing that he and May have a "really great relationship, although some people don't necessarily believe that."

"We are very much joined at the hip when it comes to the military. We have the same ideas, the same ideals, and there's nothing that would happen to you that we won't be there to fight for you," he told May. "You know that."

Trump hosted May at the White House days after he took office. But he recently cancelled a trip to London to celebrate the opening of the new U.S. Embassy. Trump and May also traded criticism last year over his retweets of a far-right group's anti-Muslim videos.

Britain is eager to strike a free-trade deal with the U.S. after it leaves the EU in 2019. U.S. Treasury Secretary Steven Mnuchin said Thursday that U.S. is ready to negotiate an "attractive" trade deal with Britain once that happens.

The president is set to address the forum Friday. He also hosted a dinner with European business leaders and will meet with other world leaders, including Rwandan President Paul Kagame, during his two-day stop.