neighbouring country; neighboring country; adjacent country
隣国との貿易が近年増加した。
Trade with the neighboring country has increased in recent years.
国境紛争が隣国との関係を悪化させた。
A border dispute worsened relations with the neighboring country.
隣国から難民が流入して深刻な社会問題になっている。
An influx of refugees from the neighboring country has become a serious social issue.