All West Bank annexation proposals are illegal—and put core international principles at risk
In late October, Israel’s Knesset voted in favor of two bills calling for annexation of the West Bank. One called broadly to annex all illegal Israeli settlements in the West Bank, while the second was a more limited proposal to annex the illegal settlement of Ma’ale Adumim, near Jerusalem. While these votes are just the first in a series before these bills become law, and there likely is not enough support to actually enact them, they are an important development in the mounting support in Israel for West Bank annexation.
However, this growing conversation in Israel—and the Knesset bills pushing towards West Bank annexation—fails to recognize that any annexation proposal is illegal under international law. This is not open debate. Under current international law, annexation is always illegal, under all circumstances. While politics certainly play into international responses to annexation, Russia’s annexation of Crimea—widely condemned by the West—is just as illegal as any potential Israeli annexation of the West Bank.
This article lays out international law prohibiting annexation before discussing international responses to Israeli proposals for annexing the West Bank. Should Israel actually seek to implement any annexation plan, all other states have a legal obligation to not recognize Israel’s annexation as legal or otherwise aid or assist in it. Recognizing, aiding, or assisting in any annexation both violates international law and risks jeopardizing foundational principles in international law, thereby undermining the law and increasing the risk of annexation in other contexts.
What is annexation, and what does international law say about it?
Annexation is a state’s forcible acquisition of territory of another state or recognized non-self-governing entity. Annexation is distinct from other modes of acquiring territory, for example by cession through mutual agreement, by means of prescription, or by accretion or natural development of new territory.
International law has not always prohibited annexation. Prior to World War I, there were no restrictions on the rights of states to wage war on other states and forcibly acquire territory. Peace treaties concluded at the end of World War I resulted in annexation—the transfer of territory from the defeated Central Powers, to the victorious Allies or new states.
However, the law began to change in response to World War I. Seeking to establish a new world order with international peace and security and prevent wars of aggression, which had just cost millions of lives, the League of Nations Covenant called for member states to “respect and preserve … the territorial integrity” of other member states and restricted the ability to wage war. However, the League of Nations proved ineffective at preventing the next war of aggression in World War II, including the scale of territorial occupation and annexation that cost tens of millions more lives globally.
Following World War II, states collectively founded the United Nations (UN) as a second attempt to establish a new world order with international peace and security. The UN Charter doubled down on preventing wars of aggression and forcible acquisition of territory. Article 2(4) requires all member states to “refrain … from the threat or use of force against the territorial integrity … of any state” except in self-defense (Article 51) or pursuant to a UN Security Council decision (Article 42). By prohibiting the use of force, Article 2(4) makes annexations illegal for all 193 UN Member States and prohibits states from recognizing as valid territorial changes by other states’ annexation.
The UN Charter reflects customary international law (legal obligations arising from established practice, rather than written texts, which all countries are required to abide by), and thus annexation is prohibited under customary international law. Further, the prohibition of aggression is a “peremptory norm of general international law (jus cogens),” or “a norm accepted and recognized by the international community of States as a whole as a norm from which no derogation is permitted.”
The prohibition against aggression relates to annexation in that it prohibits the use of armed force by one state against another—acts that often precipitate annexation—and some definitions of aggression even include “annexation by the use of force of the territory of another State or part thereof.” The prohibition of annexation under customary international law is reflected in additional sources, including binding UN Security Council resolutions 242 (1967), recognizing the “inadmissibility of the acquisition of territory by war,” and 662 (1990), declaring annexations, including Iraq’s annexation of Kuwait, as “null and void,” with “no legal validity.” Additionally, UN General Assembly Resolution 2625 (XXV) states that “territory of a State shall not be the object of acquisition by another State resulting from the threat or use of force” and that “[n]o territorial acquisition resulting form the threat or use of force shall be recognized as legal. Resolution 2734 (XXV) reaffirms that “no territorial acquisition resulting from the threat or use of force shall be recognized as legal,” and regional agreements like the Helsinki Final Act of 1970 state that participating states will “refrain from any demand for, or any act of, seizure and usurpation of part or all of the territory of any participating State.”
Aside from outlier states like Russia, virtually all states recognize annexation as illegal. This is reflected in statements and discussions in 2022 regarding Russia’s attempted annexation of the Donetsk, Kherson, Luhansk, and Zaporizhzhia regions in Ukraine.
In September 2022, UN Secretary General Antonio Guterres issued an unequivocal statement that “any annexation of a State’s territory by another State resulting from the threat or use of force” violates the UN Charter and international law. In October 2022, the UN General Assembly resumed its emergency special session regarding Russia’s wholescale invasion of Ukraine to address the latest annexation attempt. Dozens of UN member states made statements in the General Assembly, which then-US Ambassador to the UN Linda Thomas-Greenfield described as sharing “the same resounding message over and over again. It is the same message shared by the Secretary-General, the one I started with: It is illegal, and simply unacceptable, to attempt to redraw another country’s borders by force.”
On October 12, 2022, the General Assembly adopted Resolution ES-11/4, which condemned Russia’s “attempted illegal annexation” in Ukraine—with 143 states voting in favor, and only five against, including Russia, joined by Belarus, North Korea, Nicaragua, and Syria under the regime of its former dictator Bashar al-Assad.
Responses to proposed Israeli annexation of the West Bank
Discussions around Israel’s potential annexation of portions of the West Bank are not new. Prime Minister Benjamin Netanyahu has said in past election campaigns that he would annex portions of the West Bank, as an attempt to appeal to right-wing Israelis. These statements have typically resulted in strong international condemnation because annexation is illegal.
Guterres said in 2020 that Israel’s threatened annexation of the West Bank, if implemented, “would constitute a most serious violation of international law.” Guterres has repeated similar statements this year—that “annexation is illegal” and “[t]he creeping annexation of the occupied West Bank is illegal”—as discussion of West Bank annexation has grown inside Israel ahead of elections next year.
The International Court of Justice also issued an advisory opinion in 2024 finding that Israel’s policies and practices—including imposition of Israeli law, construction of the wall and infrastructure, and establishment and expansion of settlements—“amount to annexation of large parts of the Occupied Palestinian Territory.” The court concluded that this annexation, or Israel’s attempt “to acquire sovereignty over an occupied territory … is contrary to the prohibition of the use of force in international relations and its corollary principle of the non-acquisition of territory by force.” While advisory opinions are not binding, they “carry great legal weight and moral authority” and are persuasive sources in national and international courts.
Other states have also condemned recent Israeli proposals to annex the West Bank and noted their illegality. Even staunch Israeli allies like US President Donald Trump, Vice President JD Vance, and Secretary of State Marco Rubio opposed the latest Knesset votes to advance annexation plans, although their statements have not condemned the annexation plans as illegal. It is an open question whether the Trump administration will maintain this hard stance against West Bank annexation proposals, especially given Trump’s 2019 recognition of Israel’s annexation of the occupied Golan Heights—an annexation that the international community recognized as illegal, is opposed by virtually every other state, and the UN Security Council condemned as “null and void and without international legal effect.”
Despite international law clearly prohibiting such action, West Bank annexation proposals are gaining traction in Israel. This is likely due to a combination of factors, including increased security concerns after the October 7, 2023 Hamas attacks and the subsequent war in Gaza, as well as an increasingly right-wing Israeli government and base, and a gamble that the Trump administration may allow (or support) West Bank annexation.
Select international lawyers have argued that West Bank annexation proposals are legal, because they dispute the idea of Palestinian sovereignty over the West Bank and/or assert that Israel has sovereign claims to the West Bank. Other arguments posit that annexation is required for Israel’s self defense, and that the Jewish people have deep historical ties to the land and thus a legal claim to it. However, these first two claims run counter to international consensus and are in the distinct minority of legal opinions; all UN bodies and virtually all countries, including Israel’s own supreme court, recognize the West Bank as Palestinian territory. And the second two arguments are contradicted by international law; the absolute prohibition against annexation has no exceptions for self defense or historical ties.
While Israeli politicians are debating West Bank annexation proposals, there must be recognition that any such proposal is illegal. Failure to recognize the illegality of annexation will help to undermine the law, while opposition to annexation can help reinforce the legal prohibition. Under international law, foreign states must reject any annexation attempts as illegal and refuse to assist or aid in annexation.
States agreed to respect territorial integrity following the two world wars because they knew the deadly consequences of wars of aggression and annexation. Failure to resist all annexation proposals or attempts, regardless of location or actor, risks further breaking the already imperfect international order—and returning to a state of heightened global conflict.
Elise Baker is a senior staff lawyer for the Strategic Litigation Project. She provides legal support to the project, which seeks to include legal tools in foreign policy, with a focus on prevention and accountability efforts for atrocity crimes, human-rights violations, terrorism, and corruption offenses.
Further reading
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Image: A boy sits next to belongings as Palestinians remove them from their homes threatened with demolition, during the ongoing Israeli military operation in Tulkarm camp, in the Israeli-occupied West Bank, July 2, 2025. REUTERS/Raneen Sawafta
