Pengilhakan atau aneksasi (bahasa Inggeris: annexation ) merupakan tindakan pentadbiran[1] dan konsep undang-undang antarabangsa mengenai pengambilalihan wilayah sesebuah negara berdaulat secara paksa oleh negara lain.[2] Umumnya ini dikira tindakan yang haram.[2] Berbeza dengan penaklukan yang memaksukan pengambilalihan kuasa terhadap sesebuah wilayah yang melibatkan pertukaran kedaulatan.[3][4] Biasanya menyusuli pendudukan tentera terhadap wilayah berkenaan.[1]
Pengilhakan berbeza dengan penyerahan kerana tidak seperti penyerahan yang dilakukan melalui perjanjian, pengilhakan merupakan tindakan unilateral yang mana wilayah dirampas oleh sesebuah negara.[5] Pengilhakan boleh disahkan melalui pengiktirafan umum oleh badan-badan antarabangsa (iaitu negara-negara lain dan pertubuhan antara kerajaan).[5][6][1]
Perkataan "pengilhakan" ini merupakan kata terbitan daripada kata dasar ilhak. Ilhak إلحاق pula merupakan pinjaman Arab: إِلحَاق, rumi: ilḥāq "penambahan" terbitan bentuk ism kata kerja dasar اَلْحَقَ alḥaqa yang bermaksud "melampirkan",[7] "menyambung", "memasukkan" atau "menghubung".
"Aneksasi" pinjaman Belanda: annexatie terbitan kata kerja annexeren serapan bahasa Perancis lanjut dari kata Latin annexus lakuran ad- "kepada" dan nectere "menghubungkan".[8]
Conquest and annexation are not synonymous either. The latter term is used within and outside the context of armed conflicts, to designate a unilateral decision adopted by a State in order to extent its sovereignty over a given territory. In many cases, the effective occupation of a terra nullius was followed by a declaration of annexation, in order to incorporate the territory under the sovereignty of the acquiring State. In the context of armed conflicts, annexation is the case in which the victorious State unilaterally declares that it is henceforth sovereign over the territory having passed under its control as a result of hostilities. This attempt at producing a transfer of sovereignty through the exclusive decision of the victor is not generally recognized as valid, both in classical and in contemporary international law. An example of a case of annexation preceding the adoption of the UN Charter is the annexation of Bosnia-Herzegovina by the Austro-Hungarian Empire in 1908. The annexation was not recognized by the major Powers and required a modification of the 1878 Treaty of Berlin which had simply granted Austria-Hungary the right to administer the territory. Another example is the annexation of Ethiopia by Italy in 1936. Examples of purported contemporary annexations are the Golan Heights annexed by Israel in 1980 and Kuwait by Iraq in 1990, both declared null and void by the Security Council, or the incorporation of Crimea and the City of Sebastopol in the Russian Federation.
Unlike cession, whereby territory is given or sold through treaty, annexation is a unilateral act made effective by actual possession and legitimized by general recognition.
Ontleend aan Frans annexer ‘aanhechten’ [1277; Rey], ‘bijeenbinden’ [14e eeuw; Rey], ‘inlijven’ [14e eeuw; Rey], afleiding van het bn. annexe ‘verenigd’ [ca. 1265; Rey], ontleend aan Latijn annexus, verl.deelw. van annectere, gevormd uit → ad- ‘aan-, naar-’ en nectere ‘verbinden’...CS1 maint: multiple names: editors list (link)