BEIJING — A jump in violent crime in Chinese towns near the border with North Korea has prompted the authorities in China to organize civilian militias to help secure the largely unprotected border, a state-run publication has reported.

The militias, described by the publication, China Defense News, are part of an enhanced system to keep villagers safe from North Koreans, some of them armed soldiers and border guards crossing into China in search of food and money.

Last month, a North Korean soldier killed four people during a robbery attempt in Yanbian, a prefecture in Jilin Province, which shares a 300-mile border with North Korea. According to accounts in the state news media, the soldier fatally shot two older couples in their homes and wounded another resident. The suspect was subsequently captured by the Chinese police, and last week, Beijing lodged a formal complaint with the North Korean government in Pyongyang.

The killings have strained a relationship frayed by North Korea’s erratic diplomacy and its continued pursuit of a nuclear arsenal, leading to increased tensions in northeast Asia.