“缓和紧张局势”可以翻译为“ease/alleviate/reduce the tensions” 或 “defuse/mitigate the tense situation” 。
例如：
Both sides should make efforts to ease the tensions.
双方都应努力缓和紧张局势。
We need to take measures to alleviate the tense situation between the two countries.
我们需要采取措施缓和两国之间的紧张局势。