A more thorough explanation:

Definition: A deserter is a soldier who leaves their national military service with the intention of not fulfilling their military obligations, either permanently or for the duration of a military operation. It can also refer to a person who illegally abandons a military force, often by seeking refuge in a foreign territory or by joining another military force.

Examples:

• During the Vietnam War, many American soldiers deserted and fled to Canada to avoid being drafted.
• In 2019, a North Korean soldier crossed the heavily guarded border into South Korea, becoming a deserter from the North Korean military.
• A soldier who leaves their post during a battle and does not return is also considered a deserter.

The examples illustrate how a deserter is someone who intentionally leaves their military service and does not fulfill their obligations. In the case of the Vietnam War, soldiers deserted to avoid being drafted and sent to fight in the war. The North Korean soldier deserted by crossing the border to seek refuge in South Korea. In the third example, the soldier left their post during a battle, which is a form of desertion and can have serious consequences for the soldier and their unit.