DAVOS, Switzerland -- 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" 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."

A Palestinian official called Trump's "language of dictation unacceptable." Nabil Abu Rdeneh, a spokesman for Palestinian President Mahmoud Abbas, said the Palestinians are "ready to engage in negotiations" and committed to a peace process "based on a Palestinian state with east Jerusalem as capital."

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.

Trump's comment 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 celebrating global cooperation and free trade.

It wasn't immediately clear what money Trump was referring to in his threat. 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.

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 U.N. body undertakes a "fundamental re-examination."

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."

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.

Trump seemed eager to dispel concerns about his global leadership.

During an earlier meeting Thursday with British Prime Minister Theresa May, Trump insisted their relationship isn't strained and the U.S. and U.K. "are very much joined at the hip."

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

Trump hosted May at the White House days after he took office. But he recently canceled 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.

Trump's "America First" agenda and aversion to multilateral trade agreements would seem at odds with a global summit stressing free trade and international cooperation.

But Mnuchin, who is leading the largest U.S. delegation ever to attend the exclusive gathering, said "America First' means working with the rest of the world."

"It just means that President Trump is looking out for American workers and American interests, no different than he expects other leaders would look out for their own," he said.

The president is set to address the forum today.