Pirates manage to board ships operating a long way from the coast and then guide them closer to the shore
A surge in piracy near Somalia has increased threats to shipping already under pressure from maritime blockades and conflict due to the US war with Iran.
Two cargo vessels were seized in the Gulf of Aden within four days last week, rising to at least 13 the number of ships attacked since the start of the year and triggering unprecedented drone strikes against the pirates.
It is the biggest escalation in hijackings in more than a decade, renewing concern about security in this region vital to international trade.
"Piracy is always a crime of opportunity," says Omar Mahmood, a senior Somalia analyst for the International Crisis Group (ICG), "and right now the pirates see an opportunity."
That opportunity comes from the impact of the war on regional waterways further north.
Iran and the US continue to battle over control of the strategic Strait of Hormuz.
And Tehran's Houthi allies in Yemen have imposed a targeted blockade in the Bab el-Mandeb Strait, which controls access to the Red Sea. This is focused on a dispute with Saudi Arabia but heightens insecurity for international shipping.
"I guess the pirates believe that with those two external events in Hormuz and Bab el-Mandeb, they believe that the international forces will be dedicated to those crises instead of looking for pirates," says Vice-Admiral Ignacio Villanueva Serrano, operation commander for the European Union's naval force that protects shipping off Somalia's coast.
The MV Lutuf, seen here near the Turkish port of Güllük last year, was hijacked on 17 August
Among the latest vessels hijacked by the pirates was a Cameroon-flagged ship, the MV Lutuf, which was attacked off the coast of Somalia's semi-autonomous Puntland region on 17 August. A few days later pirates boarded an oil products tanker, the Eritrean-flagged MT Sibu 1, in waters near Yemen, on the other side of the Gulf.
The capture of the Lutuf has triggered unexpected consequences.
Thirteen men allegedly belonging to a network that supplies the pirates on the ship have been killed in two drone strikes since 18 August. No one has said they are behind the attacks, but local officials blamed them on Turkey, saying the vessel was carrying Turkish weapons.
The Lutuf is now among six vessels being held for demands of millions of dollars in ransom, four of which are anchored near the fishing town of Bander Beyla known as a hotbed for piracy, the BBC has learned.
That is nowhere near the peak levels of hijackings 15 years ago that cost the global economy billions of dollars. In 2011 Somali pirates carried out more than 200 attacks and held hundreds of crew members hostage.
