To examine the scope of PUF and PATBF, acts constituting attempts to acquire territory by force and their contexts which contribute to the violation of the two prohibitions are analysed, and possible scenarios based on the combination of these elements will be examined in the search for possible thresholds for their violation. If a State deploys armed forces to another State’s internationally recognised territory and takes measure to annex it, it is likely to violate the PUF and PATBF. The 2024 ICJ Advisory Opinion applied PATBF to the annexation of occupied territory which was not treated as another State’s territory and seems to indicate that PATBF may apply to an area which has potential to become another State’s territory. However, it is not clear to what extent PUF and PATBF apply to acts in an area subject to competing claims. If States ‘A’ and ‘B’ have competing claims over an area of land, and B deploys armed forces there, it may violate the prohibition of use of force (PUF) as a means of settling international issues. If PATBF denies the acquisition of territorial ‘title’ rather than ‘control’ by force, when B has a stronger title, it would not violate PATBF. If so, PATBF has a narrower scope of application than the PUF as a means of settling international issues. As contextual elements, A’s ‘peaceful administration’, mentioned by the Eritrea–Ethiopia Claims Commission, over the area may contribute to B’s violation of PUF. If A has not used force in establishing the administration and B has not protested to it, the peaceful establishment of A’s administration should contribute to B’s violation of PUF. If B has become aware of A’s administration but has not protested, or the administration had continued for a long period without protest, these factors should further contribute to B’s violation of PUF, and possibly also of PATBF. Even if B’s deployment of armed forces succeeds in creating fait accompli without causing damage, it may still violate PUF and PATBF depending on circumstances. In responding to the violation of PUF and PATBF, third States might be put under political pressure, but what they do in the critical historical juncture will be reviewed in the future, and they should bear in mind that their response will have an impact on the course of international law.