hard border
noun [ C ] uk/ˌhɑːd ˈbɔː.dər/ us/ˌhɑːrd ˈbɔːr.dɚ/
（国家之间）设有边防的边界，硬边界
a border between countries that is strongly controlled and protected by officials, police, or soldiers, rather than one where people are allowed to pass through easily with few controls
Introducing a hard border between the two countries could affect tourism. 在两国之间引入设防边界可能会影响旅游业。