Mrs Hillary Clinton and Mr Donald Trump are criss-crossing America in the last frantic weeks of the presidential election campaign. But events will not stand still, while "America decides". On the other side of the world, the United States has just suffered a significant strategic reverse.
That setback is the apparent decision by the Philippines to switch sides in the emerging power struggle between the US and China. On a visit to Beijing last week, Mr Rodrigo Duterte, the President of the Philippines, announced a "separation" from the US and a new special relationship between his country and China.
In one of the odder diplomatic pronouncements of an odd year, Mr Duterte proclaimed in the Great Hall of the People in the Chinese capital: "There are three of us against the world - China, Philippines and Russia. It's the only way." This statement was greeted by warm applause from his audience.
Mr Duterte has a tendency to shoot his mouth off. In an appearance soon after taking office, he made headlines by calling US President Barack Obama the "son of a whore".
But there is more than mere bluster involved in the Duterte pivot. The Filipino leader has also said that he intends to end military cooperation with the US.
Joint naval patrols in the Pacific will apparently come to a stop, as will joint counter-terrorism operations on the southern island of Mindanao. Some American strategists are worried that the Philippines might even now become a base for the swiftly expanding Chinese navy.
[In one of the odder diplomatic pronouncements of an odd year, Mr Duterte proclaimed in the Great Hall of the People in the Chinese capital: "There are three of us against the world - China, Philippines and Russia. It's the only way." This statement was greeted by warm applause from his audience.
Mrs Clinton, in particular, will understand the significance of all this. A central theme of her period at the State Department was an effort to bolster America's position in Asia and the Pacific. It was Mrs Clinton who proclaimed in 2010 that the US has a "national interest" in freedom of navigation in the South China Sea. This statement outraged the Chinese, whose famous "nine-dash line" on oceanic maps appears to claim that almost all of the South China Sea lies within Beijing's territorial waters.
As Mrs Clinton told Goldman Sachs, in a speech given in 2013 and recently leaked, she is worried that China's maritime claims will give it a "chokehold on sea lanes and also on the countries that border the South China Sea". Those concerns have since been further stoked by China's programme of "island" building in the disputed waters.
The Philippines was at the centre of America's strategic and legal efforts to loosen China's potential chokehold over the South China Sea. Some of the tensest disputes in the sea - such as arguments over the ownership of Scarborough Shoal - involve a face-off between China and the Philippines. It was Manila that brought a legal challenge against Beijing's claims over the South China Sea, winning a ruling at an international tribunal in July.
This ruling is crucial to Washington's argument that its dispute with China is not a crude power struggle but rather an effort, by the US, to protect the international legal order in the interests of all.
On a purely strategic level, the Philippines is (or was) also vital to America's efforts to counter the military facilities that China seems to be building on its artificial islands. Earlier this year, Manila and Washington agreed to increase America's military presence in five bases on Filipino territory, including an airbase on the island of Palawan, very close to the disputed Spratly Islands. Those US-Philippine agreements now look likely to be revoked.
More broadly, America's moral case for "standing up to China" looks much weaker if China's own neighbours no longer seem so worried by its territorial claims.
Some American strategists take comfort from Mr Duterte's obvious eccentricity. They argue that, in the long run, the Philippines will rediscover its strategic interest in seeking the protection of Uncle Sam. But it is also possible that Mr Duterte, for all his wild man antics, is actually part of a larger trend in South-east Asia.
Next year, the Philippines will lead Asean. And this will happen just as two other important US allies in the region - Thailand and Malaysia - have begun to tilt towards China. The military coup in Thailand in 2014 led to a downturn in relations between Bangkok and Washington, as the Americans called for a swift return to democracy and the Thai generals resisted. Last year, Thailand announced the purchase of Chinese submarines.
Datuk Seri Najib Razak, the Prime Minister of Malaysia, has also looked to Beijing for succour as he attempted to fend off corruption investigations in the West.
Faced with all these setbacks in South-east Asia, the US will be on the lookout for some new diplomatic and strategic opportunities. One country that seems certain to continue to push back against Chinese dominance of the region is Vietnam. This month, the USS Frank Cable and the USS John S. McCain became the first two American warships to visit the Vietnamese naval base of Cam Ranh Bay since the end of the Vietnam War in 1975.
At the height of that war, Cam Ranh Bay served as a crucial base for both the US navy and air force in the fight against North Vietnam.
It is a historic irony, and a sign of how the rise of China is changing Asia, that Vietnam could yet invite the US military back to Cam Ranh Bay - this time as an ally, not an enemy.
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