Hello. As satellite images suggest unusual North Korean activity in the buffer zone with the South, my BBC Verify colleagues analyse what's going on. We're also examining what's behind hundreds of reported deaths during this year's Hajj pilgrimage to Mecca. Three wildly varying - but equally compelling - personal stories are among my picks for you this week. And I did so badly in this week's quiz, I might punish myself with the sort of dip taken by Australians to mark the winter solstice - read about that below.

QUESTIONS ANSWERED

Images reveal North Korea's border 'wall'

Satellite images appear to show walls, as well as cleared land - which could represent a violation of the years-long truce. Credit: BBC

A South Korean official said recently that its military had identified North Korean activity related to the "reinforcement of tactical roads, the laying of mines and the clearing of wasteland" in the Demilitarised Zone (DMZ) separating the two nations. BBC Verify examines what has been going on.

What is the Demilitarised Zone?

The DMZ is a 4km (2.5 miles) wide buffer zone between North and South Korea, who are still technically at war having never signed a peace treaty. The DMZ is split in two, with each side controlled by the respective nations.

What's been happening there?

BBC Verify commissioned high-resolution satellite imagery of a 7km stretch of the border as part of a project to look at changes North Korea was making to the area. These images appear to show at least three sections where barriers have been erected near the DMZ, covering a total of about 1km close to the eastern end of the border. These structures were not visible in an image captured in November 2023.

So, what’s behind the activity?

Dr Uk Yang, a military expert at Seoul’s Asan Institute for Policy Studies, told the BBC: "Recently, North Korea has been setting up walls 2-3m (6-10ft) high, and they don't look like the anti-tank walls." Dr Ramon Pacheco Pardo, of Kings College London, says: "North Korea doesn’t really need more barriers to prevent a strike from the South but by erecting these border barriers, the North is signalling that it doesn’t seek reunification."

• Border violation: North Korean soldiers briefly crossed the DMZ on Tuesday, for the second time in a week. South Korea fired warning shots but said it believed they inadvertently crossed while fortifying the border.

• Take a look around: Foreign correspondent Jean Mackenzie's video - from March - takes you as close to the border as possible to offer a glimpse of what life is like in the DMZ.

EDITOR'S PICKS

THE BIG PICTURE

What's behind the Hajj pilgrimage deaths

Indonesia said more than 200 of its nationals had died, while India said 98 people were known to have died. Credit: Getty Images

Hajj is the annual pilgrimage to the holy city of Mecca that all financially and physically able Muslims must complete at least once in their lifetime. About 1.8 million people have taken part this year, Saudi Arabia says. But hundreds are feared to have died, with several countries opening investigations.

• 'She was totally abandoned': BBC Arabic's Sally Nabil hears from the family of a 70-year-old Egyptian woman, who died during the pilgrimage that she had funded by selling her jewellery.

And finally... in Australia

Our last newsletter mentioned Britons enjoying fine weather for the summer solstice but it was a chilly affair for Australians marking their winter equivalent. Still, some 3,000 brave souls stripped naked to plunge into the River Derwent, in Tasmania. If you don't mind some mild nudity, take a deep breath and watch how they dealt with the 12C (53.6F) water.