A sign for tourists shows the direction to Jerusalem, Amman, Baghdad and Damascus among other destinations at an army post on Mount Bental in the Israeli-annexed Golan Heights on March 22. (Jalaa Marey/AFP/Getty Images)

On Thursday, President Trump tweeted his intention to recognize Israel’s sovereignty over the Golan Heights, territory that Israel annexed from Syria in the wake of the 1967 war. For decades the United States, along with the entire international community, has refused to recognize Israel’s annexation, instead treating the Golan Heights as temporarily occupied territory.

While commentary has largely focused on the effects Trump’s announcement will have in the Middle East, this shift in U.S. policy has global implications, as well. Trump’s position on the Golan Heights is inconsistent with what scholars call the territorial integrity norm, the principle that denounces territorial conquest as a legitimate instrument of international politics. Trump’s announcement is likely to weaken the norm of territorial integrity, and in the process, undercut the U.S. ability to deter and punish states that engage in territorial expansion.

The norm of territorial integrity

The territorial integrity norm stipulates that states may not use force to alter interstate boundaries. Before 1945, forceful territorial conquest was largely seen as legitimate: After all, states depended on territory for their security and wealth, and thus seizing territory to augment natural resources, expand their population, or build more secure boundaries, was a tempting prospect.

By the 19th century, norms were changing. States in Latin America sought to order their relations around recognition of each other’s sovereign claims to territory. By 1945, the rabid expansion of Hitler’s Germany and imperial Japan made clear to the United States and its Western allies the dangers of territorial conquest. As they built the postwar order, these states enshrined the territorial integrity norm in the U.N. Charter, mandating that all members must “refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state.”

Even if Israel’s motives were defensive when it occupied Syrian territory, which it claims, its annexation of the Golan Heights after the 1967 war violated this norm of territorial integrity. For this reason, for more than 50 years the United States has refused to recognize the annexation, seeking instead to broker a deal that would give the Golan back to Syria in exchange for a lasting peace.

Trump’s recognition of Israel’s sovereignty over the Golan Heights is inconsistent with the U.S. traditional commitment to territorial integrity. Studies suggest that his departure from this norm could have three effects.

1. First, Trump’s position could weaken the norm itself.

Norms are only as powerful as actors that support them. A weakening norm of territorial integrity could have significant changes on global conflict; a strong territorial integrity norm has had far-reaching effects on international politics.

Most notably, after 1945, territorial conquest declined sharply. While approximately 80 percent of wars from 1648 to 1945 led to territorial distribution, after 1945 that dropped to 30 percent. Moreover, after 1945 states became less likely to make territorial claims, and, when they did challenge boundaries, their claims were less likely to spark military conflict. A weakened norm, then, could lead to an uptick in territorial violence.

2. U.S. rejection of the territorial integrity norm in the Golan could weaken broader efforts deter territorial expansion.

U.S. commitment to territorial integrity was designed in part to send a consistent signal to opponents that it would not tolerate territorial revision through force. The effects of this commitment have not been absolute — both Russia and China, for example, continue to engage in “land grabs” in Crimea, Ukraine and the South China Sea.

Even in these cases, however, research suggests that strong norms of territorial integrity have ensured that these land grabs remain limited, confined to “gray areas” where sovereignty is already contested and ambiguous. If the United States weakens its commitment to territorial integrity, this weakens its position on deterring Russia in the Baltics and China in the South and East China Seas and Taiwan.

3. Finally, Trump’s position on the Golan Heights will likely provoke charges of inconsistent and arbitrary enforcement of norms.

The United States has used its position as a champion of territorial integrity to mobilize support against violators. By recognizing Israel’s claims as legitimate, the Trump administration opens up space for Russia and others to portray the United States as a hypocrite, willing to abandon the norm of territorial integrity when interests serve.

Hypocrisy carries costs. When states are inconsistent in their normative claims, it tends to be difficult to mobilize support for their policy. In 1991, the United States championed an international coalition to roll back Iraq’s conquest of Kuwait. In 2014, the United States persuaded the international community to level devastating sanctions on Putin’s government after Russia invaded and annexed Crimea. Future efforts may fail if the United States appears to act only out of self-interest.

Trump’s shift on the Golan Heights will likely undercut efforts to build a lasting peace with the Palestinians and may even unsettle Israel’s treaties with Egypt and Jordan. But the questions Trump’s tweet raises are also global. Territorial integrity has become “a basic rule of coexistence” in world politics. With that rule under fire, the institutions of the contemporary order are at risk of being overturned.

Stacie Goddard is Professor of Political Science and faculty director of the Madeleine K. Albright Institute at Wellesley College. Her book, When Right Makes Might: Rising Powers and World Order, was published by Cornell University Press in 2018.