Beneath the raging protests in Palestinian communities on the West Bank and in Gaza, and the harsh criticism levied by America's closest European and Arab allies, many were left wondering: Why?
Why did US President Donald Trump turn decades of US foreign policy on its head to recognise Jerusalem as the capital of Israel and order the relocation of the US Embassy to there?
In his own statements, Trump said the move merely recognised the "reality" of where Israel already operates its government.
Senior Administration officials insisted that the decision was meaningless in the context of hoped-for Middle East peace negotiations and emphasised that most issues disputed between Israel and the Palestinians remained on the table.
None suggested a concrete US national security objective that was furthered by the move, or indicated that it was part of a strategy for achieving the peace deal that Trump has said is a primary foreign policy goal.
Instead, a decision on which players in the region said they were not consulted, and many of his own senior aides advised against, fulfilled a campaign promise and buttressed a reputation for unconventional thinking that Trump clearly sees as an asset.
In a briefing for reporters, David Satterfield, the acting assistant secretary of state for the region, largely avoided the "why" question, except to restate Trump's "reality" formulation and note repeatedly that the President had acted on what he "believes".
Near the end of his first year as leader of the free world, Trump clearly believes that on this, and on other major international issues facing the United States, he is doing an excellent job.
In remarks after his lengthy trip to Asia last month, Trump spoke of "this great American comeback" and declared that "America's standing in the world has never been stronger than it is right now".
Trump clearly has his fans, among them Israel's Government and European populists who have cheered his uncompromising stands against immigrants.
Some Arab and Asian governments, and Trump supporters in Congress, have applauded what they see as his tough, uncompromising stands against North Korea and Iran, although his strategy for dealing with them remains unclear.
The President has correctly noted that Nato is glad he made an issue of member failure to meet defence spending targets, propelling some to spend more, faster.
But he has few real admirers among alliance leaders, whom he has alienated on issues ranging from his jettisoning of painstakingly negotiated climate and trade agreements, his reluctance to champion the alliance's mutual defence pact, and his disdain for the Iran nuclear deal.
In public remarks last week, German Foreign Minister Sigmar Gabriel spoke for many Western European allies when he said that, far from boosting its leadership role, the US has withdrawn from the international stage and now sees the world "as a fighting community where everyone has to seek their own advantage".
After Trump, Gabriel said, his country's relations with America "will never be the same".
At home, senators John McCain, (R), and Benjamin Cardin, (D), at the weekend bemoaned US relinquishment of its position as the world's standard-bearer for human rights. In a letter to Trump, they noted he had never even mentioned the issue publicly while visiting repressive regimes in Asia.
Trump's reluctance to criticise Russia - whether tied to the ongoing investigation of what US intelligence has said were Moscow's efforts to get him elected, or his oft-repeated belief that close US-Russia relations are good for the US - has made many lawmakers uncomfortable. Many of his strongest supporters in Congress were part of an overwhelming vote last northern summer to impose new sanctions against Russia, despite the President's strong objections.
To the extent the US has left a void, others are stepping in.
As Russia has expanded its influence in the Middle East, China's role is growing in Africa and Latin America, and it is soon expected to match or overtake the US in many aspects of global leadership. As a hefty US trade deficit has grown significantly under Trump, President Xi Jinping has said China is poised to give developing countries a "new choice" as his country takes "centre stage" in the world.
Even longtime Arab partners in the Middle East have voiced outrage over the Jerusalem decision, with many saying the US can no longer claim the leading role in bringing the Israelis and Palestinians to a negotiated peace.
Asked whether the Jerusalem decision would impede achievement of the "ultimate deal" Trump has said he wants to forge there, Satterfield responded, "I can't make that judgment at this point".
Others were more certain. "We don't see this as a good idea in any way possible," said a senior official in the government of a close US ally in the Middle East. "That's why we say this is something that had support within the US political establishment. We look at it as a domestic-driven position more than anything else," because "it doesn't make any sense on the peace-process level."
What Trump's decision did accomplish was checking off a campaign promise to two important constituencies - wealthy conservative Jewish contributors, and motivated white evangelicals who voted for him despite his moral failings and a lack of real connection to that community.
To some foreign policy experts, campaign positions that Trump believes got him elected - and expects will do the same next time around - are the basis for many of his major foreign policy initiatives.
"Mr Trump's foreign policies serve his political purposes, not the nation's interests," Robert Zoellick, a former World Bank president and senior official in the George W. Bush Administration, wrote late last month in the Wall Street Journal. Trump's populism, Zoellick wrote, looks for enemies and "feed[s] off grievances and impatience with traditional politics."
In a piece in the Wall Street Journal the next day, Bard College professor Walter Russell Mead took a different view.
Trump, he said, is responding to the exhaustion and unwieldiness of the "gassy globalism" that has been America's post-World War II leadership strategy. This "vast, misshapen edifice," in which the US claims leadership on virtually every international issue, he said, was unsustainable.
Jon Alterman, senior vice-president of the Center for Strategic and International Studies, posited a third rationale. Trump's foreign policy, he said in an interview, "is instinctual and not rational" and is rooted in "his delight in defying conventional wisdom".
Decisions like the Jerusalem recognition, Alterman said, are "not for strategic purposes, but for matters of personal style and instinct," even as they may disrupt the Administration's own diplomatic initiatives.
"I think he has interpreted the last three years," since he first contemplated a presidential run, "as reinforcing the idea that he is both unusually gifted, and rewarded, because he is unconventional," Alterman said.
"All of that may well be true," said Ivo Daalder, president of the Chicago Council on Global Affairs and author, with James Lindsay, of a forthcoming book titled How America Abdicated its Global Leadership Role.
"But what convinces me is that he's had a particular view on how America engages with the world," dating back many years, Daalder said, recalling a full-page New York Times ad Trump purchased in 1987 to charge that America was being "laughed at" for giving others a free ride at its expense.
As the post-World War II US has carried the burden of multilateral leadership, "we have not been a normal country when it comes to engagement in the world," Daalder said.
"If we're going to be a normal country," he said, the US will have to become accustomed to "being on the losing side" of international issues "more often than we're used to being".