Power Play - The prime minister's trip abroad was billed as a "trade mission," but was most productive leader-to-leader behind closed doors.

In an increasingly unstable world, it's hard to overstate the importance of strengthening relationships with like-minded partners, particularly in the Indo-Pacific.

Jacinda Ardern denies any connections have suffered due to the long Covid-19 hiatus, but the value of sitting down in a room face-to-face has been obvious.

And on that count, the visit was a success.

Speaking at the end of the trip before heading home later today, Ardern said she had not expected to be allowed so much time with the leaders of Singapore and Japan.

In Singapore, Ardern had a warm exchange with Prime Minister Lee Hsien Loong at the grand Istana palace and emerged with a new climate change commitment.

But it was Ardern's visit to Japan which delivered the most significant development - a plan to share more "top secret" material between both countries.

Ardern said Prime Minister Fumio Kishida was "genuinely interested" in New Zealand's positions, even noting how the government had changed the law to impose sanctions on Russia.

The torrid global landscape and shifting geo-political allegiances have underscored the need to bolster security ties.

Russia's invasion of Ukraine has heightened tensions over fears its actions could embolden China closer to home.

News broke this week that China had inked a security pact with Solomon Islands, a deal the PM has previously called "gravely concerning".

Japan has expressed concern about China's assertiveness in the Pacific too but is particularly worried about activity in the East China Sea near the Japanese-controlled Senkaku islands.

One can quickly see the value of an information-sharing arrangement.

As the world's third largest economy, Japan is a powerful friend to have.

That is true too for trade as New Zealand looks to reduce its reliance on Beijing and drum up business in different markets.

Japan and Singapore rank fourth and fifth among New Zealand's trading partners already, but there is plenty of room to grow that. Together, they represent roughly $15 billion of two-way trade. China alone exceeds $33 billion.

The trip offered little in the way of increased market access as New Zealand already holds comprehensive free trade agreements with both countries.

Its success on trade then can perhaps be judged only by the travelling business delegation.

The endless "memoranda of understanding" witnessed by Ardern grew tiresome but could yet bear fruit in the future.

Zespri certainly enjoyed the profile boost from Ardern's visit, though arguably its dancing mascots - known as the 'Kiwi Brothers' - did more for the cause.

Ardern stressed the value of bringing exporters along, allowing them to build relationships on the ground.

"Our trade agreements essentially open the door, but it's not a given that then products flow through it," she said.

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• Japan and NZ to negotiate intelligence-sharing deal after Ardern and Kishida meet amid tensions with China

The tourism sector must be pleased with the number of times Ardern invited captive audiences to come visit New Zealand when its borders open further next month.

When asked to give two words to sum up the trip, she eventually quipped "May second" - the date she had been repeating ad nauseum.

This part of the world has certainly not returned to normality with Covid-19 restrictions tougher than that seen in New Zealand.

In Singapore, people must still scan in at restaurants, and social gatherings are capped at 10 people. In Tokyo, mask-use is required both in- and outdoors, and many venues require temperature checks.

Japan's strict entry-requirements saw three members of the delegation cut their experience short after they failed a PCR test due to an old infection.

Ardern told media she did not believe the restrictions had curtailed her agenda, but they speak to the persistent challenge of Covid-19.

This trip is just the first on a packed travel schedule for Ardern this year as New Zealand lifts its own Covid restrictions at home.

Ardern has flagged visits to Australia, the United States and Europe - all of which carry huge potential for New Zealand when it comes to both trade and security.

New Zealand is nearing the end of negotiations for a free trade deal with the EU, and the US has signalled it could launch a new Indo-Pacific Economic Framework as early as May.

Comparatively, this "trade mission" carried somewhat lower stakes but has served a worthwhile first showing after nearly 800 days out of practice.