The Second Nagorno-Karabakh War, and its lingering aftermath, have put the fundamental and largely unsettled question of the jus ad bellum in the spotlight: when part of one state’s territory is occupied by another state for a prolonged duration, can the former state have lawful recourse to military force to recover its land? Prior to the 2020 conflict, the Nagorno-Karabakh region was widely regarded as belonging de jure to Azerbaijan, but as being unlawfully occupied – for more than 25 years – by Armenia. Accordingly, was Azerbaijan entitled to claim self-defence to lawfully recover it, even though the pre-2020 territorial status quo in the region had existed for more than a quarter of a century? In addition, could Azerbaijan invoke self-defence again in the near or distant future to recover those remaining parts of territory that continue to be outside of its control now that a new ceasefire is being enforced in the region? The answers to these questions have ramifications that extend far beyond the Caucasus, being of relevance for a wide range of pending conflicts around the globe. Upon closer scrutiny, the present authors believe that a negative answer is in order.

中文翻译：

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非法：诉诸武力收复被占领土和第二次纳戈尔诺-卡拉巴赫战争

第二次纳戈尔诺-卡拉巴赫战争及其挥之不去的后果，将战争法这一基本且很大程度上悬而未决的问题置于聚光灯下：当一个国家的部分领土被另一个国家长期占领时，前一个国家能否拥有合法诉诸武力收复其土地？在 2020 年冲突之前，纳戈尔诺-卡拉巴赫地区被广泛认为在法律上属于阿塞拜疆，但被亚美尼亚非法占领超过 25 年。因此，即使 2020 年前该地区的领土现状已经存在了超过 25 年，阿塞拜疆是否有权要求自卫以合法收回？此外，阿塞拜疆能否在近期或遥远的将来再次进行自卫，以收复由于该地区正在实施新的停火而继续不受其控制的剩余领土？这些问题的答案所产生的影响远远超出了高加索地区，与全球范围广泛的悬而未决的冲突有关。经过仔细审查，目前的作者认为否定的答案是正确的。