Last month I led a small delegation from the Council to Japan and South Korea. The trip included visits to two of our Sister Cities — Kurashiki and Songpa — and to the atomic bombing remembrance ceremonies in Hiroshima and Nagasaki. We also talked to New Zealand tourism and trade representatives in Seoul and Tokyo.

For me, the trip was something of a pilgrimage and underscored some of my fundamental beliefs — ideas about peace, about understanding and about how individuals, small groups and perhaps small cities can make a real difference.

I said it when we unveiled the firefighters’ memorial, and I’ll say it again. When people or countries stop talking there’s every chance that the very worst will happen. Walking around Nagasaki and Hiroshima drives that home in a terrifying way, looking at the amazing museums and listening to the stories of what happened to people when the A-bombs went off in August 1945.

Christchurch has a great history of individuals and small groups advocating for peace, against war and nuclear weapons. Over the years they’ve made a difference, driving the change in public attitudes which led to this city, and eventually New Zealand itself, becoming nuclear-free and working to push that message out around the world. There’s been some discussion recently suggesting that our Sister Cities links aren’t worthwhile. The talk’s mainly been about money, what it costs and what we get back. That is the wrong way to look at it, it’s very short-sighted.

For a start, I don’t think the figures being quoted are accurate about which cities spend what, but more importantly, the real payback isn’t financial. It’s not about money, it’s about understanding, about building relationships. What we get from Peace and What we from these international exchanges is long-term deposits in the peace bank.

The relationship with Kurashiki, on the Inland Sea coast of Japan’s main island Honshu, is our longest-running. Christchurch and Kurashiki have been sisters for 30 years and, really, the relationship doesn’t have a lot to do with local body politicians.

Yes, the city councils support it and we host each other from time to time. But the relationship’s built on ordinary people, thousands of people over the years — young musicians, artists, cultural groups and plain ordinary citizens — travelling between each city, hosting visitors in their homes and quietly learning about each other, about the things that make them different and the ways in which they are the same. It’s about understanding.

Songpa is one of the cities that make up Seoul, the South Korean capital. Of Christchurch’s six sisters, Songpa’s the youngest. Songpa itself is young. It’s on the south side of the Han River and didn’t exist just a few decades ago. Today, it’s thriving – a big, modern city whose people are grappling with many of the same issues we’re concerned about in Christchurch – the environment, quality of life, traffic management.

Here too, it is ordinary Korean people with ties to Christchurch are the fuel that the sister-city relationship runs on.

Over time, it may be that the city councils of Songpa and Christchurch can encourage projects which would satisfy a cost accountant, but the real strength — the long-run payback — will be in the exchanges of young people and the mutual understanding those relationships create.

On behalf of Christchurch I signed a memorandum of friendship and understanding with Hiroshima’s Mayor, Tadatoshi Akiba. That was on 7 August, the day after the A-Bomb memorial ceremony. The agreement isn’t a commitment to anything specific. It’s more a statement that Christchurch, as a Peace City, and Hiroshima share the same ideas about the value of peace.

Mr Akiba’s city, along with Nagasaki, started the Mayors for Peace network which now has 520 cities in more than 100 countries as members. I am a member. He says, and I agree, that cities and their people can make national politicians sit up and take notice.

In his speech at the A-Bomb memorial (Hiroshima calls it the Peace Memorial Ceremony) Mr Akiba asked people everywhere to do more to counter the threat of nuclear weapons and war.

“Hiroshima calls on politicians, religious professionals, academics, writers, journalists, teachers, artists, athletes and other leaders with influence,” he said. “We must establish a climate that immediately confronts even casual comments that appear to approve of nuclear weapons or war. To prevent war and to abolish the absolute evil of nuclear weapons, we must pray, speak and act to that effect in our daily lives.”