They would be damaging the environment by cutting down the trees. Trees play a vital role in the environment as they clean the air of carbon dioxide and help stop erosion as well as provide food and habitats to various organisms. Were they to be cut down, they would stop being these things to the environment.
As for the people, the solider betrayed their trust because as soldiers, they are meant to protect the people of the country that they are from. If a country's soldiers begins to attack the livelihood and property of the country's citizens as well as killing its own people, they have violated the oath they took to protect those same people.
