Reuters

AS SOON as they heard that Captain Richard Phillips had been rescued by the American navy—snipers had killed three pirates holding him at gunpoint on a lifeboat—the 19-strong crew of the Maersk Alabama whooped for joy. The cargo ship's horn hooted, flags were flown and flares fired to celebrate the release on April 11th of the skipper who had given himself up to win the release of his crew.

Two days earlier, French commandos had also been in action. They freed four of their compatriots, including a three-year-old boy, held hostage aboard a yacht, the Tanit (pictured above). One captive, Florent Lemaçon, was killed.

The United Nations' envoy to Somalia, Ahmedou Ould-Abdallah, said such stern military measures “are sending a strong message to the pirates and, more importantly, to their backers”. But for the moment the strong message has been met with strong defiance. Some pirates said they would kill French or American sailors that fall into their hands. There is little sign, so far, that attacks have been deterred. Since Captain Phillips's release, at least four more ships have been attacked—two of them were captured in the Gulf of Aden, the area most closely patrolled.

Some 15-20 ships, ranging from bulk carriers to fishing vessels, along with about 300 sailors, are currently being held by Somali pirates. So far they have attacked ships for gain rather than out of ideology. They have almost always treated their hostages well while negotiating ransoms. But Vice-Admiral William Gortney, who commands American naval forces in the region, concedes that things could turn nastier as foreign navies resort to greater force. “This could escalate violence in this part of the world. No question about it,” he says.

The combination of one of the world's busiest shipping lanes (20,000 ships a year pass through the Gulf of Aden) alongside the world's most utterly failed state makes the waters off Somalia the most prone to piracy. Ransoms of up to $3m make it an attractive profession. Money earned can go towards buying faster boats and fancier navigation equipment. Some captured vessels are used as “mother ships”, floating pirate bases from which speedboats can be launched against merchant vessels sailing hundreds of miles offshore. One was captured by the French navy on April 15th.

The International Maritime Bureau, a private-sector outfit, counted 111 pirate attacks off Somalia in 2008, nearly triple the previous year's number. That figure includes the capture of 42 vessels, among them the Sirius Star, a Saudi supertanker, and the MV Faina, a Ukrainian ship carrying tanks. So far this year, pirates have been more active but less successful. In 68 attacks they have captured only 18 ships, often small ones.

This is partly due to the presence of more foreign warships, including some dispatched by the European Union, NATO, an American-led coalition and by countries such as China and India wanting to protect their own vessels. However, their effect may be merely to shift the problem from the Gulf of Aden to the Indian Ocean.

President Barack Obama says America is “resolved to halt the rise of piracy”. But how? Piracy off the Horn of Africa is of a different order from other maritime troubles, for example along the coast of west Africa where America is also busy (see article). Somali pirates operate up to 800 miles out to sea, loiter for weeks and even attack at night. There are now 20-odd warships patrolling 1.1m square miles (2.8m square km) of ocean off Somalia, two-thirds the area of the EU. “There is a lot of water out there. Twenty assets do not make much of an impact,” says Commodore Tim Lowe, the British deputy commander of the American-led naval coalition. By one assessment, it would take about 140 warships fully to secure the Gulf of Aden, and several times that number to protect the seas off eastern Somalia.

So merchant ships are encouraged to look after themselves. Those making the 500-mile passage through the Gulf of Aden are told to stick to a designated “transit route” and to bunch up for protection in the most dangerous areas and times of day. In this way vessels, particularly slow ones with decks that are low off the water, can be “monitored” (but not escorted) by warships. Such measures have made it harder but not impossible for pirates to capture ships, particularly as some of them prefer to go it alone to save time (and money).

Some suggest protected convoys, but this would slow down shipping and require more warships than are available. Others propose arming merchant seamen, but that could provoke a spiral of bloodshed. For now, passive self-defence is generally the norm: barbed wire, fire hoses to try to push pirates away and, above all, an alert crew to spot attacks as early as possible to let the ship take evasive action.

One Western naval officer says placing all warships under a single command, say of the UN, and adopting the same rules of engagement would make the most of the existing forces. Hillary Clinton, America's secretary of state, suggests trying to freeze pirates' assets. In the end, as she acknowledges, the solution is not at sea but on land. Somalia needs a viable government to control its territory and shores. But that is a long way off. Western countries, after their experiences in Iraq and Afghanistan, are in no hurry to send soldiers to Somalia.

For now, merchant shipping's best friend may be the weather. The south-west monsoon begins at the end of May and blows until August or so, making life much harder for pirates. Let it blow soon.