China has given more than 60,000 soldiers a new order: planting trees to create new forests.

According to Asia Times, a regiment of the People’s Liberation Army and China’s armed police force have been removed from their posts in northern border areas. The task is part of efforts to tackle high levels of air pollution.

The project is a big one. China plans to grow 6.66 million hectares of new forest this year, having already created 33.8 million hectares (338,000 square kilometres) of forest in the past five years, says Zhang Jianlong, head of the State Forestry Administration, in a report from Reuters. The country wants to increase the area of land covered by woodlands from 21.7% in 2016 to 23% by 2020, according to China Daily.

The majority of the reassigned soldiers will work in the heavily polluted Hebei Province, where three new state forests are planned. The province is often blamed for producing the fumes and smog that cover Beijing and northern China, and has committed to increasing its forest coverage to 35% by the end of 2020.