President Trump’s announcement that “it is time for the United States to fully recognize Israel’s Sovereignty over the Golan Heights” — which stops just short of actually doing so — is being received as yet another example of, as the New York Times wrote, his “willingness to flout diplomatic orthodoxy and shake up a debate over the Middle East that has changed little since the 1970s.” That’s true, but it greatly understates the significance of his action. Trump is subverting one of the most fundamental pillars of the post-1945 world order: the principle that no nation can change international boundaries by force.

Territorial integrity was listed as both the first and second war aims agreed to by President Franklin D. Roosevelt and British Prime Minister Winston Churchill in the 1941 Atlantic Charter: “First, their countries seek no aggrandizement, territorial or other; second, they desire to see no territorial changes that do not accord with the freely expressed wishes of the peoples concerned.” It was then enshrined in Article 2 of the 1945 United Nations Charter: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state.”

The United States insisted on territorial integrity, because it did not want to see a repeat of the 1930s when Japanese aggression against China, Italian aggression against Abyssinia, and German aggression against Austria and Czechoslovakia presaged the coming of World War II. Acting on this principle, the United States never recognized Russian sovereignty over the Baltic states or, today, over Crimea. U.S. troops fought to prevent South Korea, South Vietnam and Kuwait from being swallowed by aggressors. The United States was even willing to risk nuclear Armageddon to prevent the conquest of tiny West Berlin.

The sacred principle of territorial integrity lies at the heart of U.N. Security Council Resolution 242, adopted with U.S. and Israeli support in 1967 after Israel fought the Six-Day War to preempt Arab aggression. This resolution called for “Withdrawal of Israeli armed forces from territories occupied in the recent conflict,” but by omitting “the” in front of “territories,” it left vague which land was to be evacuated. The resolution went on to call for “acknowledgment of the sovereignty, territorial integrity and political independence of every State in the area and their right to live in peace within secure and recognized boundaries free from threats or acts of force.”

By accepting this resolution, the Arab states and eventually the Palestinian Authority de facto agreed to Israel’s right to exist. The exact contours of its borders were to be left to an agreement between the parties. This led to Egyptian and Jordanian recognition of the Jewish state, and to lengthy negotiations with the Palestinians over the West Bank and Gaza Strip and with the Syrians over the Golan Heights. No “final status” agreement was ever reached with the Palestinians, and no agreement at all with the Syrians, but 242 served as the basis of all peace talks since 1967.

Now Trump has killed 242 just as surely as he has killed all standards of presidential decorum. And to what end? No one has been contesting Israeli control over the Golan Heights. Trump is stirring up a controversy where none existed and thereby handing a present to Hezbollah and Bashar al-Assad by allowing them to posture as the resistance to Israeli occupation rather than be recognized as what they are — the butchers of their fellow Muslims.

Trump took this momentous step as a pre-election present to his pal, Israeli Prime Minister Benjamin Netanyahu, who shares with him many of the same campaign donors (e.g., Sheldon Adelson), the same political supporters (U.S. evangelical Christians), the same disdain for the rule of law (Netanyahu is on the verge of being indicted), and the same affection for right-wing extremists (Netanyahu has made common cause with far-right parties in Israeli politics and with the far-right leaders of Central Europe).

Perhaps just as important from Trump’s perspective is Netanyahu’s willingness to flatter him with Pence-esque fervor. As a result, Trump is giving the Israeli leader a valuable gift that any normal president would have held back in return for substantial Israeli concessions on settlements.

Trump claims his decision on the Golan Heights is just like his decision last year to move the U.S. Embassy to Jerusalem — a move I supported. But he is wrong. The embassy move had been endorsed by Congress and promised by president after president, because West Jerusalem has been a part of the Israeli state since Day One. No previous president promised to recognize Israeli sovereignty over the Golan Heights, and indeed President Ronald Reagan supported a 1981 U.N. Security Council resolution calling the annexation “null and void,” because all previous presidents had adhered to the principle of territorial integrity.

No longer. With this typically thoughtless and impetuous act, Trump is opening a Pandora’s box where states are allowed to change international borders by force. He is making not just Netanyahu but also Vladimir Putin and Xi Jinping very happy.

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