A series of large heroin seizures have been made in South Africa since 2016, but the country is just one of the pitstops on Africa's heroin highway.
The African continent is geographically situated between opium production and consumer states.
The route goes through Pakistan and Iran to their coastlines, known as the Makran Coast. From there, the drug is loaded onto dhows which cross the Indian Ocean to transit states in either Africa or Asia, from where it is rerouted to its final destinations, mostly in Europe. The second phase of the journey can be by sea, land or air.
The dhows are large vessels often used for fishing explorations and able to undertake long journeys.
To avoid detection, the dhows either dock at island ports or remain out at sea. The heroin is then collected by smaller boats and taken ashore. The East and Southern African coastline has many inconspicuous islands to serve this purpose, which was also one of the factors luring cocaine traffickers to the cocaine plagued country of Guinea Bissau.
The coastline from Kenya to South Africa is long, with porous borders, weak maritime surveillance, weak law enforcement capacity and corrupt officials willing to turn a blind eye. There is also a large diaspora connecting different regions to East and Southern Africa.
These factors attract traffickers and mean that managing the heroin trade in South Africa is fraught with challenges. Chief among them is the transnational nature of the heroin trade, the likely increase in local heroin use and the ability of the networks who run the trade to outsmart and outperform regional law enforcement entities and their limited resources.
Changing circumstances, changing routes
There are three primary heroin trafficking routes out of Afghanistan; the Balkan Route, the northern route and the southern route. The Balkan route, stretching overland from Afghanistan to the Balkan countries and Western Europe, has experienced the bulk of heroin trafficking.
Research shows that law enforcement efforts as well as conflicts have pushed some of the trade away from the Balkan route to the southern route and maritime trafficking, where law enforcement is mostly absent. Despite an increase in the southern route's popularity with traffickers, it remains the least used of the three.
In 2010, a surge in large maritime heroin seizures in East Africa first highlighted Africa's role in the southern route, especially the use of Kenya, Tanzania and Zanzibar as transit zones.
In 2014, 1,032 kg of heroin was seized from a dhow off Mombasa. It was the largest ever seizure of the drug outside of Afghanistan and its neighbouring countries.
As seizures have continued, international attention and law enforcement efforts in and around East Africa have increased. This is probably what caused traffickers to increasingly turn to landing points in Southern Africa.
South Africa is attractive for other reasons too. Drug traffickers are able to exploit the country's efficient financial and transport infrastructure.
Indian Ocean heroin trafficking
Law enforcement on the southern route is mainly concerned with disrupting maritime heroin shipments before they reach the shore. The biggest law enforcement effort has come from the Combined Maritime Forces Combined Task Force 150.
It is a fleet of 31 international navies mandated to patrol the Western Indian Ocean to disrupt terrorist activities and financing. This includes disrupting heroin trafficking on the high seas. Between 2013 and 2016 the force seized 9.3 tons of heroin.
The task force patrols a vast area - 2.5 million square miles across the high seas, extending as far as Mozambique. South Africa must, therefore, rely on its own navy and intelligence to detect shipments that outwit the Combined Task Force.
But the biggest obstacle to exposing the criminal networks running the southern route has been the Combined Task Force's lack of jurisdiction to arrest heroin trafficking crews in international waters. This has resulted in the practice of the Combined Task Force throwing the heroin overboard and setting the crew and their vessel free.
If heroin can be seized in territorial waters, the national laws of the country apply and prosecutions can follow.
Land based seizures in South Africa
It is likely that dhows are only dropping off heroin as far as Mozambique because they would attract suspicion if they travelled as far as South Africa.
Land based seizures in Kenya, Tanzania and Mozambique have shown that heroin is broken up when it reaches the shore and then transported onward by road. This explains the seizure of smaller amounts of heroin being transported in cars and trucks from Mozambique to South Africa.
A recent heroin seizure in Overberg in the coastal province of the Western Cape has provided new insights into what researchers and law enforcement have only been able to speculate - that southern route heroin is also being transported to and from East and Southern Africa in containers. Containerised heroin seizures have been made elsewhere along the southern route.
The heroin was found on a wine farm, hidden among boxes of wine intended for container shipment to Europe. This finally offers a more concrete link to container trafficking on the southern route, which would be harder to detect than dhows.
But lots of questions remain unanswered. These include: where did the shipment come from? Was it a single large shipment which entered at a harbour or smaller shipments that were consolidated on the wine farm? If so, which overland route was used? Was corruption involved? Is local heroin use increasing due to increased trafficking through the region?
What needs to happen?
Rooting out corruption and minimising the pool of potential small scale traffickers could be a good place to start. But the problem is much bigger than South Africa and encompasses many elements that increased law enforcement can't address. One factor, for example, is increased local heroin consumption.
To understand, and respond to heroin trafficking networks there needs to be a coordinated effort that brings together production, transit and consumer states.
In the meantime, South Africa needs to increase its vigilance in local ports and along borders.
Carina Bruwer receives funding from the Global Initiative against Transnational Organized Crime and the Social Science Research Council.