The rescue of Capt. Richard Phillips from the clutches of Somali pirates is a welcome bit of news in a world that's otherwise been short on happy developments. However, the enormous skill of the Navy SEAL snipers who pulled off the extraordinary feat merely throws into relief the extent to which combating piracy solely at sea is destined to be a difficult endeavor with poor prospects for success. The ocean is extremely large, and the number of people who can successful execute a boat-to-boat sniper shooting is very small. The international antipiracy fleet is heavily clustered in the immediate vicinity of Somalia, but as the journalist Xan Rice has observed, the Indian Ocean is “an area too large for foreign navies to cover effectively."

Meanwhile, not all daring...