But in recent years Japanese soldiers have landed in Papua New Guinea on a very different mission - training the national forces' military band to play new tunes and old standards such as "Abide With Me", culminating in an appearance at the Royal Edinburgh Military Tattoo in Sydney in October.

"Heart-to-heart" aid, one Japanese Ministry of Defence official called it.

Aimed at building trust and people-to-people contacts, this aid is the face of a much broader effort by Tokyo to counter Beijing's attempts to reorder the region.

Japan, like Australia, has watched anxiously as China offers to lay an undersea communications cable to the strategically sensitive Solomon Islands, or to build critical roads within PNG.

China is focused on the Pacific islands as it seeks to extend its domain of power outward from its own shores, as part of its ambitious Belt and Road Initiative (BRI) to reshape global trade and influence in Beijing’s favour.

The People's Republic has ploughed investment into PNG’s resource sector, built a fishery on the Cook Islands, reportedly inked a deal to lease an island for a base in the Solomon Islands and resumed relations with Kiribati, where it maintains a satellite tracking centre. It is constructing office buildings and roads on Tonga, and lent heavily to Fiji following the 2006 coup.

Now Tokyo is also directing more attention and resources to the region.

“Today, Japan is strengthening its commitment to this area even more, because of its importance as the core to a Free and Open Indo-Pacific (FOIP),” Maya Hamada, principal deputy director of the Japanese Ministry of Foreign Affairs' Oceania Division, told The Age and Sydney Morning Herald.

The FOIP vision involves supporting the rule of law, freedom of navigation and the pursuit of peace and prosperity. Tokyo lists the risks to the region: piracy, terrorism, WMD proliferation, natural disasters - a vulnerability Japan shares with other Pacific island nations - and “attempts to change the status quo”.

Supporting the region's prosperity for Japan requires “improving connectivity” among the region’s fragile economies through ports, railways and roads but also institutional connectivity and people-to-people links.

"Japan has interests in the Pacific, as a maritime and Pacific power, and seeks to maintain – if not increase – its footprint in the region," said Lowy Institute research fellow Alexandre Dayant, who studies aid and diplomacy in the region.

As a democracy, he says, Japan "will do what it can to preserve and advocate" FOIP while containing  China's Belt and Road Initiative, which Tokyo "sees as a challenge".

This is welcomed in Canberra. Australia is the single largest provider of aid to the region and has initiated its own effort, dubbed The Step-Up, for similar reasons.

Considered one of Australia's "highest foreign policy priorities", the Step-Up includes support for a $2 billion infrastructure financing scheme and $500 million in climate change and disaster resilience work around the Pacific, as well as people-to-people exchanges.

Canberra is also funding the Coral Sea Cable to deliver high-speed communications to PNG and the Solomons, rendering the Chinese offer for undersea cable redundant.

The Step-Up embraces the same goals as Japan's efforts: offering an alternative to China that upholds the needs of democratic middle powers.

Unlike China’s BRI, which focuses on infrastructure and trade, Japan aims to support both hard infrastructure - ports, roads, schools - as well as “soft” infrastructure including refining local legal systems and social services such as health, medicine and education.

Tokyo has been involved in the redevelopment of Nazab Airport in PNG, fully funded the $US30 million ($44.4 million) upgrade of Apia Port in Samoa in 2018 and helped upgrade Port Vila's port facilities in Vanuatu.

It is also planning to extend and improve airstrips and facilities at Tokua airport in East New Britain in Papua New Guinea.

Last year, Japan helped complete a climate change research centre in Samoa in conjunction with the local government.

It's not all infrastructure, though. When measles broke out in Samoa, Japan sent a specialised medical term to treat children affected by the disease in December. The same month, Japan announced $US8 million in aid for Vanuatu's remote medical clinics.

In April, Japanese and Tongan officials broke ground at a $US37 million nationwide early warning system for the island nation.

Hamada, like other Japanese diplomats The Age and Sydney Morning Herald spoke to, refused to “compare the results of our cooperation with ones of other countries”. But the rivalry with China is inescapable.

China is seeking to challenge Japan’s control of the Senkaku Islands in the East China Sea. Further south, China is rapidly building up and militarising islands and reefs throughout the disputed South China Sea, giving Beijing more scope to project military power.

Envisioned as “an integrated and exclusive system”, the lavishly-funded BRI could entrench Beijing’s dominance in a region marked by fragile, aid-reliant nations.

For that reason, Tokyo in its Pacific outreach embraces “mutually complementary cooperation projects” with like-minded democracies such as Australia, New Zealand and the US.

While getting exact figures for the Pacific islands is difficult,  data compiled by the Lowy Institute shows Japan has spent $1.1 billion from 2011 to 2017 and is third after Australia ($7.5 billion) and New Zealand ($1.5 billion) over the same period. China comes in fourth, with $1.28 billion, according to Lowy Institute data.

But China's ambitions can be seen in how much it has committed to the region, calculated at $4.78 billion in 2017, up from $270 million pledged the year before.

The dollar diplomacy used to promote China’s infrastructure has proven attractive to political leaders in the developing world. A submission to an Australian parliamentary inquiry showed some Pacific island nations viewed aid from Beijing as "more effective" because it came with "no strings attached”.

Tomohiro Tanaka, deputy director of Japan's Official Development Assistance agency, an arm of the Foreign Ministry, says his country aims not just to deliver aid and infrastructure but to “disseminate ideas [and standards] of infrastructure sustainability over the world”.

“We should increase the reputation cost [for poor infrastructure],” he said. “We aim to make the international environment follow the standards.”

If the values of sustainable "quality" infrastructure are accepted by political rivals, the world is safer for Japan and like-minded democracies, the thinking goes.

This concept, first promoted by Japan about four years ago, requires projects to create local jobs, be environmentally sustainable and align with the recipient nations' own economic goals. Importantly, it embraces "debt sustainability" - in sharp contrast to the "debt-trap diplomacy" China's BRI has been accused of promoting.

"The work of influence in the region is not a zero-sum game," says Lowy's Dayant.

There are historical parallels to this approach of infusing actions with values to achieve influence.

During the Cold War, the US government sponsored the development and distribution of biology textbooks in Asia that emphasised free inquiry in science,  nudging students and educators toward Western-style freedom of thought and away from Communist dogma.

Today, with its support of FOIP, Japan is aiming aid at supporting the rule of law, and by extension open democracy. Those efforts don't always produce ribbon-cutting ceremonies, yet they can be effective in other ways.

Late last year Lowy's Dayant wrote: "Too much focus on China can lead to an under-appreciation of how Tokyo’s extensive relationships could offset Beijing’s position, particularly when considering that much like its network in Asia, Japan’s competitive advantage is 'relational rather than material'."

Japan’s view of aid is fundamentally different from Australia’s too.

Where Australia wants to see a clear benefit for projects it funds, Japan typically sees aid as integral to its own security, says Musashino University politics professor Donna Weeks.

After World War II, Japan’s pacifist constitution ruled out projection of military power, leaving it to embrace aid as a form of national security. "Sustainable development goal aid was a part of Japan's idea of what constitutes comprehensive security,” says Weeks.

Even as China powers ahead with its plan to re-orient global trade and influence through Beijing, Japan is quietly chipping away at offering alternatives and keeping lines of communication and transportation open.

Aid flows are coming and going throughout the region, says Dayant: "I believe that actors that look at the long game have the best chance to be considered as the most influential in the Pacific."

Chris Zappone travelled to Tokyo as a guest of the Japanese government.