Military operations usually are intended to catch the enemy off guard, but for weeks U.S. and allied officials have been telling reporters about their forthcoming assault on Marjah, a Taliban-held town of 80,000 and drug-trafficking hub in southern poppy-growing Helmand province.

Senior NATO commanders and top Afghan officials have openly discussed the approximate time of Operation Moshtarak - the Dari language word for "together" - the size of the force and their objectives in news conferences, interviews and press releases that have been disseminated around the world and posted on government Web sites. Leaflets have been airdropped on the town.

Though the exact time of the kickoff hasn't been disclosed, a "news article" posted Thursday on the British Ministry of Defense's site announced that operations involving "elements of the Royal Welsh, Grenadier Guards and Scots Guards" and Afghan forces "in preparation" for the Marjah attack had been underway for 36 hours.

The unusual approach, according to U.S. and British commanders, is intended to persuade Marjah's civilian population to leave or turn against the Taliban, while pressuring the estimated 2,000 insurgents to flee the town or switch sides.