Prime Minister Jacinda Ardern is expected to participate in the upcoming NATO Leaders Summit, becoming the first New Zealand leader to do so.

NATO's Secretary General, Jens Stoltenberg, has invited the leaders of Australia, Japan, South Korea and New Zealand to attend the military alliance's meeting in Spain held 28-30 June.

Anthony Albanese, Fumio Kishida and Yoon Suk-yeol have already accepted the invitation.

Ardern is expected to participate in a session focused on the Asia-Pacific region and meet with a range of foreign leaders.

While ministers, including Foreign Affairs Minister Nanaia Mahuta, have attended previous NATO meetings, this is the first time New Zealand has been invited to the Leaders Summit.

Stoltenberg said the invitation is a "strong demonstration" of NATO's "close partnership" with like-minded countries in the Asia Pacific.

NATO will set its strategy for the next decade at the summit and define the security challenges the alliance is facing and what it will do to address them.

Leaders will also discuss "strengthened" defence, further support for Ukraine and Finland and Sweden's applications for membership.

Otago University Professor of politics and international studies Robert Patman said the invitation is significant and "reflects the gravity of the international situation at the moment."

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The invitation has come at a "critical" time in Europe, he said.

"We live in such an interconnected world. We've seen in New Zealand how events far away from us, such as trans-national terrorism, can impact on our own society...

"We live in a world in which increasingly all states, big and small, are confronted by problems which don't respect borders.

"There's a recognition among NATO that although New Zealand and Australia and South Korea and Japan are geographically a long way from NATO, they share a lot in common in terms of values and in their approach to international order.

"So I think that's probably why, given the dramatic backdrop of the war in Ukraine, that we've been invited to NATO."

At the summit, Ardern will likely want NATO leaders to "reaffirm the importance of a rules-based international order, on which this country critically depends," Patman said.

Ardern also recently returned from a trip to the United States where she met with US President Joe Biden, and a trip to Singapore and Japan.