Somalia's militant Islamists remain relatively undiminished, despite a 12-year UN-backed campaign against them, largely thanks to its sophisticated web of spies, writes the BBC's Mary Harper.
Often, when I return to the UK from Somalia, I get a phone call from al-Shabab. It usually happens even before I talk to my family, while I am waiting for my luggage or in a taxi on the way home.
Once, after a trip to the south-western Somali town of Baidoa, I was given a detailed account of what I had done and where I had been.
“You walked to a bank but it was shut. You knocked on the doors and tried to open them. You took some photos,” said the man from al-Shabab, an affiliate of al-Qaeda.
“Your bodyguards were not at all professional. They were wandering about, chatting amongst themselves with their guns slung around their shoulders, instead of keeping watch over you.”
When I ask members of al-Shabab how…
