Smugglers doing a brisk trade in slaves, drugs and weapons along the jungle border between Thailand and Malaysia have been a source of tension between the Southeast Asian countries for decades. The 640km divide is also a favoured hideout for insurgents.

Now the two sides are talking about building walls from the Strait of Malacca to the Gulf of Thailand. Military leaders announced an agreement in September, saying construction could start next year. But there’s still a lot to discuss: how much to spend, how tall a barrier to build and what hi-tech surveillance to use.

It would be a rare act of co-operation between two countries that have not always been friendly. But is it really the solution? “When governments announce walls and border fortifications they are seen as addressing the problem,” says Thitinan Pongsudhirak, director of the Institute of Security and International Studies at Chulalongkorn University in Bangkok. “But a wall is misguided: it may cost a lot and lead to not much.”

Thailand and Malaysia are under pressure from both the US and the EU to crack down on human-trafficking and slavery on land and at sea. Every day thousands enter illegally, mostly Bangladeshis seeking work or refugees from among the Rohingya, a Muslim minority group in Burma. Earlier this year mass graves of migrants were found in detention camps believed to be run by human-smuggling rings on both sides; it was this discovery that spurred Thai and Malaysian authorities to act.

Patrolling the jungle and seas is a challenge, not least when border-enforcement officials are known to be involved in smuggling operations. Yet another obstacle is an insurgency in Thailand’s southern provinces, where ethnic Malay Muslim militant groups have long been fighting for their independence. “The insurgency makes the border porous and inaccessible,” says Pavin Chachavalpongpun, at Kyoto University’s Centre for Southeast Asian Studies.

There’s a sense of security that comes with a wall. But for Thailand there’s also a downside: “It could block undocumented migrant workers who are now a key part of the economy,” says Pongsudhirak. “When we need the labour, authorities have turned a blind eye. But when it becomes a security threat, alarm bells go off.”

Mansoor Naderi leads a project to grant land-ownership rights to many of the 70 per cent of Afghans who live in so-called “informal houses” built on land without proof of ownership – a plan that could lift the economy of a country struggling with an insurgency.

What issues does Afghanistan face in urban development?
Afghanistan is urbanising rapidly. Kabul was built for 350,000 people; today the population is almost for million. Some come because of conflict in the provinces, others for jobs. It’s down to us to create infrastructure across the city.

What are your plans to make Kabul a more liveable city?
We’re building parks for children to play in and safe places for families. Kabul was once known as a garden city; it’s important that we create more green areas and better preserve our historical sites.

How do insurgents' attacks and violent crimes affect your work?
The lack of security is a major impediment to our ability to plan developments. Corruption is also an issue in attracting private investment. Nevertheless, we need to move forward.

To end up where?
We have finished mapping land-use and housing across Afghanistan. This data will be used to register informal housing; eventually, residents will own their homes. Data shows that investment grows with formal ownership. We will also look at providing affordable housing, which will help create a middle class. At the moment we only have rich and poor.

Every five years since 1993, African leaders have flown to Tokyo to listen to Japan’s latest multibillion-euro aid pledge for the continent. But in 2016 the Tokyo International Conference on African Development will be held in Kenya, not Japan.

The new approach coincides with a rhetorical shift in Tokyo: prime minister Shinzo Abe is playing up his country’s role in weakening terrorist groups such as Boko Haram. It’s all part of his plan to raise Japan’s profile. The focus on Africa reflects an attempt to win friends and counter China, which has also been gaining influence with investment in the continent. Japan hopes that the goodwill could translate to broader support for the G4 too.