WASHINGTON  The first major operation launched with the additional troops ordered to Afghanistan by President Obama is devised to clear Taliban havens across a strategic southern province  and then, in a marked departure from past practice, to leave clusters of Marines in small bases close to the villagers they were sent to guard and aid, according to senior military officers.

Despite the troops’ substantial numbers and firepower, the strategy is not without risks. Indeed, on Thursday, the first Marine was killed in the operation.

Image U.S. Marines waited for helicopter transport as part of an operation in Helmand Province on Thursday. Credit... Manpreet Romana/Agence France-Presse — Getty Images

Although American and allied forces have previously swept through the province, Helmand, killing or capturing as many guerrillas as they could, often with airstrikes, the military has never before had enough ground troops to hold onto large areas that were cleared of insurgent fighters in combat operations.