The Trump administration last month formally recognized Israel’s annexation of the Golan Heights. In recent days, it has taken actions to implement that decision, such as producing maps that depict the region as part of Israel. While the US decision to recognize Israeli sovereignty over the occupied Golan Heights raised multiple political questions, perhaps the most important one is whether it undermines the international system of states. Today’s international system is based on the idea of sovereign states — meaning that the government or rulers of a country have full power over affairs within their borders. While the idea of state sovereignty is often traced back to the 1648 Treaty of Westphalia, the modern state system emerged from the ashes of the Second World War, with the creation of the UN and the end of the European colonial period. The modern global system is based on the idea that the key actors are sovereign states. The UN “is based on the principle of the sovereign equality of all its members,” according to its Charter. Another foundational principle of the modern state system is the idea of territorial integrity based on sovereign states with defined borders. The international laws and norms that underpin the global system require that states respect each other’s borders. The UN Charter says that member states should refrain “from the threat or use of force against the territorial integrity or political independence of any state.” It is not legal for a state to grab its neighbor’s land and claim it. Many who have defended Israel’s annexation of the Golan Heights have based their argument on the idea that Israel should be allowed to claim territory that it captured from an enemy in a defensive war. This seems intuitively fair to many people. However, it fundamentally falls under the idea that “might makes right” and the only constraints on states should be how much or how little power they have. In most wars, the warring parties disagree about who was the aggressor and who was the defender, so distinguishing “defensive” wars as carrying special status is deeply problematic. The 1967 war in which Israel captured the Golan Heights from Syria is a good example of disputes over who was the aggressor. The Golan Heights is not the only recent issue threatening to chip away at the principles of sovereignty and territorial integrity. Russia’s 2014 annexation of Crimea also presents a significant threat to the idea of sovereignty and permanent borders. The capture of the peninsula from a militarily weaker country also indicates a “might makes right” approach.Some would argue that the idea of state sovereignty is unimportant. The principle of sovereignty and the role of international law are highly debated among international relations theorists. Furthermore, there are many examples of violations of state sovereignty since the creation of the UN. These range from foreign interference in a country’s affairs to full-scale invasions. Failed states and governments that commit large-scale abuses, especially genocide, have raised questions about the responsibilities that come with sovereignty. The UN Charter also includes the principle of self-determination, and there are cases of territories with populations that chose to break away from their state (or who still want to). Communications technology, economic interlinkages, ideas about human rights and other developments have also affected the viability of sovereignty. Nonetheless, there are actually few cases in the modern period of sovereign states invading other sovereign states and then claiming territory. Russia’s annexation of Crimea, Iraq’s 1990 annexation of Kuwait, and Israel’s annexation of the Golan Heights are among the few examples. In the case of Iraq, the international community worked together, under US leadership, to force Iraq back into its own boundaries, therefore reinforcing the concept of state sovereignty and territorial integrity. In the last few years, however, Russia and the US have made moves that suggest a loss of interest in the principles of state sovereignty — through the annexation of Crimea and the recognition of Israeli sovereignty over the Golan Heights. Russian President Vladimir Putin has been open about this, calling in 2014 for a “new Yalta” approach that would bring several currently sovereign states into a Russian sphere of influence. Those who defend these moves might argue that they simply reflect the facts on the ground. Russia argued that it was acting to protect the rights of Russian speakers in Crimea, though they had little choice in the affair. Israel has long controlled and settled the Golan Heights. The reality is that, despite various weaknesses, a system based on state sovereignty and territorial integrity — supported by international law and norms — is essential to constraining states, especially powerful states, and to providing a degree of global stability. The global economic system depends on the idea of sovereign states. Companies seeking to invest need the stability of knowing what government they are dealing with in a particular territory. Respect for borders does not stop war, but it can prevent or limit it. Sovereignty offers some protection for most of the world’s states from aggressive, more powerful nations. The annexation of Crimea and the US recognition of Israel’s annexation of the Golan Heights are unlikely to be fatal blows to the state system. However, they come at a time when the modern state system is under increasing strain, and the clear message that neither Moscow nor Washington wants to abide by its core principle could be very damaging.