Nothing like an Asia-Pacific equivalent of the North Atlantic Treaty Organisation is in the offing, but here and there we see closer ties between countries that formerly had defence connections only through Washington.

NATO was formed after World War II as a solid defensive alliance: an attack on one member would be an attack on all. But in Asia the US preferred mainly bilateral deals, so it has separate alliances with (in order of military spending) Japan, South Korea, Australia, Thailand and the Philippines.

New Zealand was in there, too, but it dealt itself out of the ANZUS alliance in 1984 by posturing over US nuclear weapons, and it still strikes that sanctimonious pose. Meanwhile, the rest of us are attending to business.

Australia and Japan have been edging closer together since the middle of last decade. By then, both were rapidly coming to understand that China wanted overlordship of the Asia-Pacific.

In a big step, Tokyo and Canberra signed a defence co-operation agreement last year so their armed forces could better work together. There's still no alliance, but they talk of something that's moving that way, a "special strategic partnership".

Most Australians would be surprised to hear that mighty Japan says their country is its most important security partner after the US. We'd better start thinking the same way about Japan.

In particular, we should consider that Japan, a democracy, has the world's third-largest economy, is greatly increasing its defence spending, is by far the most stalwart east Asian country in resisting China and, unlike the US, can never quit the region.

A great frustration for Washington has been that Japan and South Korea do not get on, mainly because Japan thinks it has already fully apologised and compensated for World War II crimes, while few South Koreans agree.

Yet China has its ways of getting countries to put aside their differences.

In 2015 only 37 per cent of South Koreans viewed China negatively. But in the following year Beijing outrageously tried to control South Korea's defence policy, punishing it for having the hide to accept a protective US system whose radar could peer into Chinese airspace.

That and other provocations caused South Koreans' anti-Chinese sentiment to rocket. Last year 81 per cent of them viewed China negatively, according to the US think tank Pew Research.

The previous South Korean president, Moon Jae-in, electorally exploited anti-Japanese feeling and took a soft line on China. But the current president, Yoon Suk Yeol, is trying to bury history, overcome popular sentiment against Japan and move his country closer to it.

South Korea and Japan are even taking small steps in defence co-operation, which was unthinkable a few years ago.

Last year, Thailand also edged closer to Japan, with an agreement on arms exports. Still, no one seems to expect the south-east Asian country to help much in resisting the Chinese territorial and military expansion that could eventually envelop it.

The Philippines is a more interesting case. As elsewhere in south-east Asia, China's influence there is rising. But so is pressure from its aggression, so the Philippines looks intent on concluding an agreement that would open its territory for exercises by Japanese forces.

Strategic geography explains the Philippines' importance. China's maritime access to the world and its ability to project air power into the Western Pacific depend on passing through the First Island Chain. That's the great archipelago that stretches from Japan's northern islands, through Taiwan, the Phillipines, East Malaysia and Indonesia. A desire to break the chain is a major explanation for China's keenness to seize Taiwan.

The Philippines offers the closest territory from which Taiwan could be supported militarily from the south, while Japan has the islands just north of Taiwan. The Philippines is also the best place from which to threaten China's position in the South China Sea and, unlike Thailand, probably could be reinforced in wartime.

So it was alarming when Rodrigo Duterte, the Philippine's anti-American president from 2016 to 2022, shifted his country diplomatically closer to China, even as Beijing tried to take what Manila claimed as territorial waters.

But Duterte's successor, Ferdinand Marcos jnr, has allowed the US to add five bases to its existing access rights in his country. The locations of four of them were revealed in April. And - surprise, surprise - two are at the northern end of the country, close to Taiwan, and two are halfway down the eastern side of South China Sea.

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No one is saying what the bases are for, but a pretty solid guess would be that in wartime the US would use them to support launchers of strike and anti-aircraft missiles. Hiding in forests, such weapons would attack Chinese ships, aircraft and bases in the South China Sea and around Taiwan.

And now Australia pops up in the Philippines story. Last Saturday the defence ministers of Australia, Japan and the US together met their Philippine counterpart. They jointly said it was important to strengthen co-operation with Manila.

In this regard, Australia hasn't done much except to give the Philippines some surveillance drones. Quite probably, more Australian support is planned, however.

That leads us to wonder about a couple of unanswered questions from this year's Australian defence review, which mysteriously required our army to form an amphibious combat force.

It didn't say why, nor where the force was supposed to go in wartime.

Was it thinking of the Philippines?