ON THE ARABIAN SEA  Rear Adm. Giovanni Gumiero is going on a pirate hunt.

From the deck of an Italian destroyer cruising the pirate-infested waters off Somalia’s coast, he has all the modern tools at his fingertips  radar, sonar, infrared cameras, helicopters, a cannon that can sink a ship 10 miles away  to take on a centuries-old problem that harks back to the days of schooners and eye patches.

“Our presence will deter them,” the admiral said confidently.

But the wily buccaneers of Somalia’s seas do not seem especially deterred  instead, they seem to be getting only wilier. More than a dozen warships from Italy, Greece, Turkey, India, Denmark, Saudi Arabia, France, Russia, Britain, Malaysia and the United States have joined the hunt.

And yet, in the past two months alone, the pirates have attacked more than 30 vessels, eluding the naval patrols, going farther out to sea and seeking bigger, more lucrative game, including an American cruise ship and a 1,000-foot Saudi oil tanker.

The pirates are recalibrating their tactics, attacking ships in beelike swarms of 20 to 30 skiffs, and threatening to choke off one of the busiest shipping arteries in the world, at the mouth of the Red Sea.