A bedrock principle of international law is that borders can’t be changed by force. Governments cannot be rewarded for action that comes at the expense of another’s territory, and there is no time limit on such behavior, no point at which the world can acquiesce. That is why U.S. President Donald Trump’s tweet last week endorsing Israel’s claim to sovereignty over the Golan Heights, territory seized from Syria 52 years ago, was so shocking. Trump’s decision looks more like domestic politics than realpolitik and validates criticism of a U.S. decision-making process that is haphazard, ad hoc and detrimental to its national interest.

Israel took the Golan Heights, a 1,200 sq-km plateau, from Syria during the six-day Israeli-Arab war in 1967. Successive Israeli governments have argued for retention of it because of its strategic value: It provides line of sight over much of Syria — the suburbs of Damascus are visible from there — as well as access to the Sea of Galilee, a critical source of water for the region. Some 20,000 Israelis have settled in the area since it was taken by Israel; a similar number of Druze, Syrian Christians also reside there. Israel passed legislation annexing the territory, but the rest of the world has not recognized the law.

Officially the move is intended to strengthen Israel’s security. There has been an influx of anti-Israel forces such as Hezbollah or other militaries supported by Iran into southwestern Syria. U.S. National Security Advisor John Bolton explained that allowing the Golan Heights “to be controlled by the likes of the Syrian or Iranian regimes would turn a blind eye to the atrocities of Assad and the destabilizing presence of Iran in the region.” As Trump tweeted, the Golan Heights are “of critical strategic and security importance” to Israel.

Still, there is no missing the domestic politics hanging over the decision. Israeli Prime Minister Benjamin Netanyahu is facing his toughest election battle ever and Trump’s move, like the decision to move the U.S. embassy from Tel Aviv to Jerusalem, is a gift to him. Netanyahu has pressed U.S. presidents to recognize the land grab and Trump’s readiness to acquiesce is proof of Netanyahu’s influence in Washington. He is visiting the United States this week, to meet and have a private meal with Trump, and to address the annual gathering of the American Israel Public Affairs Committee (AIPAC). That high profile will play well with Israeli voters.

For Trump, the decision pays its own dividends. It allows him to cast himself as the president who could do what his predecessors did not (ignoring why they “failed” to act). It confirms his standing as Israel’s best friend in the U.S., which will help him with evangelists and Jewish supporters of Israel as the U.S. heads into its own presidential campaign in 2020.

That is dangerously short-term thinking. The U.S. move changes nothing for Israel. Washington remains an outlier among nations and United Nations condemnations of the land grab remain. The move has inflamed sentiment in the region, however. A Syrian foreign ministry source said that the Damascus government was “more determined to liberate it by all possible means no matter what.” Turkish President Tayyip Erdogan denounced the move in a speech to the Organization of Islamic Cooperation, adding that “we cannot allow the legitimization of the occupation of the Golan Heights.”

Other reactions were no less critical. A German government spokesperson condemned “unilateral steps.” The French foreign ministry concurred, noting that “The recognition of Israeli sovereignty over the Golan, occupied territory, would be contrary to international law, in particular the obligation for states not to recognize an illegal situation.” Iran called the move “illegal and unacceptable.” In Tokyo, Chief Cabinet Secretary Yoshihide Suga said Japan’s position of not recognizing annexation of the territory by Israel remains unchanged.

Trump’s announcement, like the decision to move the U.S. embassy to Jerusalem, strips away what remained of the veneer of neutrality that the U.S. enjoyed as a moderator in peace talks. Palestinians and other concerned parties believe that Washington has taken sides in the conflict and anticipate the Golan move to be a precursor to a similar declaration regarding the West Bank, also seized in 1967 and vital to any future Palestinian state.

Yet even if the world does not recognize any shift in status of the Golan Heights, Trump’s announcement has implications for other land grabs: Russia’s annexation of Crimea, Moscow’s claim to the Northern Territories — a group of islands off Hokkaido seized by Russia since 1945 — or Chinese claims to the South China Sea. Foundational principles demand complete adherence; any departure from the norm can quickly create more cracks in the facade and its ultimate collapse. Trump’s announcement last week is another contribution to the erosion of international law.