Díjūn yǐ zhànlǐng le jiāotōng yàochōng, qiēduàn le bǔjǐ xiàn.
The enemy had occupied the strategic traffic junction, cutting off the supply lines.
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要冲 is a somewhat formal or literary term, more common in historical, military, and geographical contexts. In everyday speech, 交通枢纽 (traffic hub) or 关键位置 (key position) are more common alternatives.
