Story highlights About 300 Marines will replace US Army advisers in Helmand

Marines will be tasked with training and advising Afghan soldiers and police

Washington (CNN) Approximately 300 Marines will deploy to Afghanistan's Helmand Province this spring, returning to the scene of some of the fiercest battles in America's 15-year-long engagement there.

The commandant of the Marine Corps, Gen. Robert Neller, said Thursday that the troops have "no delusions about the difficulty and the challenges they're going to face."

The Marines will be tasked with training and advising Afghan soldiers and police in the volatile opium-rich province. Afghan security forces there have been locked in constant clashes with Taliban insurgents, who have managed to reestablish a significant presence.

Helmand sits in the country's southwest. While geographically large, it is very rural and contains only about 3% of the Afghan population.

"The enemy has fought hard for Helmand," Gen. John Nicholson, the commander of US forces in Afghanistan, told reporters at the Pentagon last month.

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