As Donald Trump began the longest and arguably most consequential tour of Asia an American president had attempted in a generation - one that could soothe or inflame nuclear tensions and set the course of this century's great power politics - there were good reasons for America's friends in the region to be nervous.
According to critics, US President Trump's "America First" outlook marks a retreat from the world stage by a country that not long ago considered itself to be "the indispensable nation".
Trump's lack of engagement can be seen in the US State Department - America's vast engine of diplomacy - which according to Trump sceptics has been rendered either idle or impotent over the past 12 months. Twenty-one of 23 of the State Department's crucial assistant secretary of state positions remain unfilled or held by acting officials, Foreign Policy magazine recently noted, and 48 ambassador postings are still empty.
Staggeringly, roles unfilled include a permanent assistant secretary of state for East Asian and Pacific affairs, and even under the threat of war on the Korean Peninsula, an ambassador to South Korea.
Last month it took days for the State Department to unconvincingly deny a report that the Secretary of State, Rex Tillerson, had called Trump a "f---ing moron".
If the White House has a broad Asia strategy, it has not yet revealed what it might be. So expectations for this trip have been mixed.
Trump's personal rhetoric suggests he is both easily riled by criticism and swayed by flattery.
So who would emerge from Air Force One as it touched down in Japan and South Korea, in China and at APEC talks in Vietnam? Would it be tough-guy Trump from Twitter, or deal-maker Trump from The Apprentice? Marking his first anniversary in the White House, would a more seasoned, nuanced, presidential Donald Trump make his way to the tarmac?
The first time Trump met the Japanese prime minister, Shinzo Abe gave him a gold-plated golf club. Since then the two leaders have made much of their shared love of the game, which became a key part of the backdrop to Trump's visit at the beginning of the week.
Donald Trump, right, and Japanese Prime Minister Shinzo Abe, left, play golf at the Kasumigaseki Country Club in Kawagoe, north of Tokyo, last Sunday. Photo: AP
Japanese media also made much of the fact that, when Abe tripped and fell in a sand trap, Trump marched on, either unaware or unaffected.
"Abe was ignored when he fell over backwards. He served Trump a lot of delicious food but in return all he got was being forced to promise to buy more weapons," one Twitter observer lamented.
That talk of a weapons deal turned out to be significant. Trump had marked his arrival in Japan by voicing his displeasure at two things. The first was America's $US55 billion trade deficit with Japan, and the second was Japan's decision to not escalate tensions with North Korea by attempting to shoot down two test missiles which North Korea fired through its airspace.
Trump managed to bind the two issues when he appeared with Abe at the Akasaka Palace in Tokyo. "He will shoot them out of the sky when he completes the purchase of lots of additional military equipment from the United States," Trump declared. "The Prime Minister of Japan is going to be purchasing massive amounts of military equipment, as he should.
"It's a lot of jobs for us and a lot of safety for Japan," he added.
So far no deal is in place, but Japanese observers noted that Trump's rhetoric on the issue may help Abe overcome domestic political resistance to his plans to increase Japan's military capabilities.
Trump and South Korean President Moon Jae-in, right, have lunch with US and South Korean troops. Photo: AP
Months before his arrival in South Korea, Trump had divided local opinions with his furious Twitter rhetoric against the North Korean dictator Kim Jong-un.
In response to North Korea's rapidly advancing nuclear weapons testing program, Trump in August had fired off a Tweet saying that North Korea would "be met with fire and fury like the world has never seen" if it continued on its course.
Kim responded that plans were being drawn up for a missile strike on the American territory of Guam. War on the Korean Peninsula appeared to be a live and terrible possibility.
America has long had a critical and disputed role in South Korean affairs, where it is rightly seen as both crucial guarantor of security and potential threat to peace. South Korea, like no other country on earth, depends on an ally that is at once staunch and potentially dangerous.
As North Korea ramps up a missile program designed to place US cities in range of its nuclear weapons, some South Korean security analysts fear a scenario known domestically as "Korea passing", whereby the US might elect to launch a preventive war against the North with devastating consequences for the South, to ensure that American civilians never come under threat.
Barack Obama's North Korea policy, which the White House dubbed "strategic patience", has been widely viewed in South Korea as a failure. Though Trump's tougher line is now viewed by many as more effective, his unpredictability remains a cause for concern.
During a briefing with Fairfax Media last week, South Korea's First Deputy Chief of National Security Strategies, Sang-chui Lee, said his government had come to rely on its suite of close ties with US government agencies rather than solely on Trump's Twitter feed.
"We should not simply look at President Trump's wording in itself," he said. "We should take into consideration also the messaging by diplomatic staff, represented by Secretary of State Tillerson and [that of] Secretary of Defence Mattis as well, so we need to have a comprehensive view of the entire US government's policy."
But in the days before arriving in Seoul, Trump moderated his language, and his address to South Korea's parliament hit many of the marks his hosts were hoping for.
"History is filled with discarded regimes that have foolishly tested America's resolve," he said. "Anyone who doubts the strength or determination of the United States should look to our past and you will doubt it no longer. We will not permit America or our allies to be blackmailed or attacked."
But beyond assurances of American determination Trump used the speech to outline what has emerged as the regional strategy for dealing with the North Korean threat - the steady increase of diplomatic and economic pressure, led by the US and China, to force North Korea to return the negotiating table.
Trump neither raised nor ruled out the possibility of proceeding with talks in return for a freeze in North Korea's program, which many analysts view as the most viable course of action.
By the time he reached Beijing on Wednesday, Trump's complaints about unfair trade deals with Asian nations had almost become routine.
But Japan and South Korea were security allies. China was a strategic rival.
In the one place where Trump, who had once accused China of stealing US manufacturing jobs and being a currency manipulator, was expected to push hardest on unfair trade, he pulled his punches this week.
China's trade imbalance with the US was shocking, a massive distortion, he had earlier said. But this week, after emerging from two hours of talks with China's ascendant leader, Xi Jinping, Trump declared to shocked reporters: "I don't blame China. After all, who can blame a country for being able to take advantage of another country for the benefit of its citizens ... I do blame past [American] administrations."
Donald Trump with Xi Jinping in Beijing on Thursday. Photo: Bloomberg
A signing ceremony with 28 US business executives had been arranged for the travelling TV cameras to announce $US253 billion in deals, including the purchase of 300 Boeing aircraft by a Chinese company, to give Trump a "deliverable" on trade for audiences back home.
But the list of US complaints he ran through as he spoke to the business audience - lack of market access into China for US firms, forced technology transfers and intellectual property theft - remained talking points, without a solution.
On North Korea, Trump thanked Xi for his "hard work". But the question of whether China would countenance going further than United Nations Security Council Sanctions and cut all trade ties - or its vital oil pipeline - was also left hanging.
Beijing had rolled out the red carpet and it had worked a treat. After an evening of personal hospitality with Xi and his wife, Peng Liyuan, in the ancient seat of Chinese emperors, Trump was effusive on their "great chemistry" and friendship.
White House senior adviser Jared Kushner at a bilateral meeting in Beijing's Great Hall of the People on Thursday. Photo: AP
The Centre for Strategic and International Studies' senior adviser Bonnie Glaser says: "I can only speculate that Trump believes praising Xi and the Chinese people will get China to make the moves on trade and North Korea that he wants."
Perhaps, but other analysts have read Trump's language as a result of the White House's lack of a China policy.
On board Air Force One before arriving in Beijing, Trump officials boasted to the travelling US press pack they had "the gear on board" to ensure Trump could tweet in China. But where was the crack China policy team?
Arabella's father, Trump's son-in-law Jared Kushner, accompanied Trump to Beijing, despite media reports that he may not because of a perceived conflict of interest with his family's real estate dealings and Chinese investors.
Kushner is regarded as having a more favourable approach to Chinese co-operation than White House China hawks.
Asia Pacific? Or Indo Pacific?
A security official stands on guard outside the venue for the Asia-Pacific Economic Cooperation CEO Summit in Da Nang, Vietnam. Photo: AP
Trump's Asia tour is expected to take a harder policy edge as he addresses APEC to flesh out a US vision for what the administration is now calling the Indo Pacific. He then moves on to the East Asia Summit, where freedom of navigation and the South China Sea will be the simmering issue.
At both forums, the US and China's strategic rivalry in the region is expected to be on display. Both Xi and Trump will be courting Vietnam over its opposition to China's island-building in the South China Sea.
The White House has signalled that Trump's recent use of the term Indo Pacific, and not Asia Pacific, will be explained at APEC as encompassing India as a counter-balance to China in the region.
More confusion on this message arose from Trump's meeting with Xi in Beijing. Xi said the two men had agreed that the US and China were the key countries with great influence in the Asia Pacific. "The Asia Pacific is large enough to embrace China and the US," he said.
In Seoul, South Korean President Moon Jae-in had declined to sign on to Trump's definition of the Indo Pacific, local media reported a day after Trump had left.
The other major theme at APEC and ASEAN is expected to be free trade. It is an area where China is quickly filling the leadership vacuum left by the United States.
In the face of that vacuum, Prime Minister Malcolm Turnbull plans to use the 21-nation APEC summit to resuscitate some version of the Trans-Pacific Partnership (TPP) trade deal that Trump abandoned within days of taking office.
Officials of 11 remaining countries, including Australia, have been discussing the deal on the sidelines of APEC since last Monday.
Several countries, including Canada and Malaysia, have shown little enthusiasm for moving quickly ahead on the deal chiselled out under Barack Obama's administration as a key part of his "pivot" to Asia.
But others, led by Japan, Australia and Singapore, are arguing that a revived TPP could eventually prod the US to return to the deal.
Turnbull said before leaving Australia he hopes an outcome on the deal can be secured in Da Nang "that will bring significant benefits to Australian businesses" in a trade zone with a combined GDP of $12.4 trillion.
Malcolm Turnbull joins Vietnamese-Australian chef Luke Nguyen for breakfast in Da Nang, Vietnam. Photo: Alex Ellinghausen
Those countries see Trump's arrival at APEC as an opportunity for him to explain how the US can be seen as a reliable economic and security partner.
Also in Vietnam, Trump is expected to address speculation he wants to revive a so-called quadrilateral strategic alliance consisting of the US, Australia, India and Japan to counter China's growing strength.
Geoff Raby, a former ambassador to China and the chairman of Geoff Raby & Associates, has warned Australia has a lot to lose and nothing to gain from an alliance that will infuriate China and flies in the face of decades of sensible diplomacy.
Carl Thayer, an expert on South-east Asia at the University of New South Wales, said Trump's every word and action will have considerable weight in the eyes of regional leaders, who will be looking for answers to fundamental questions such as "can he be trusted? Can he provide reassurance that the US will remain engaged in Asia Pacific? Or will his chop-and-change brand of strategic uncertainty become the new normal?"
In talks ahead of the summit, APEC trade and foreign ministers struggled to reach agreement with their US counterparts on language on free trade and protectionism to be used in a joint statement by their leaders this weekend.
"The US opposes multilateral trade agreements and the other economies are not happy," an official involved in negotiations in Da Nang told Reuters.
Both Trump and Turnbull will attend ASEAN and EAS summits in the Philippines next week, and there disagreements over security issues will supplant disagreements over trade among member states.
The Philippines and Vietnam want Trump to remain tough on China's aggressive build-up of islands in the flashpoint waters of the South China Sea.
Turnbull wants to work closely with Trump on a range of security issues, including preventing Islamic State gaining a foothold in the region, and halting proliferation on the Korean Peninsula.
After that Xi will return to a nation where his authority grows by the month, while Trump will confront his party's first serious electoral losses since his unlikely election win 12 months ago. Turnbull will return to a parliament and government whose very legitimacy is now under a darkening cloud.
The rest of the region will be left to consider a big question, says Professor Thayer.
Will November 2017 "mark the moment the United States ceded leadership in the Asia Pacific because Trump lacks the experience and conceptual ability to think strategically rather than transactionally?".