Complementary to the prohibition on the use of force was the principle of uti possidetis juris, which means that post-independence, a newly formed state is to have the same borders as it had prior to independence. This principle was fundamental to the vast postwar movement of decolonization. The borders of what had been colonies were often the arbitrary result of European rivalries, having little to do with the ethnic identities of local residents. Still, the system of state building had to adhere to those borders. The same principle was followed in the breakup of the Soviet Union. That people of the same ethnic group lived on the other side of the border was no excuse. Indeed, such claims were precisely the target of this principle. Defending ethnic Russians in Ukraine is about as much a legal entitlement as defending Germans living in other states was in the 1930s.

Take the most fundamental principle of the post–World War II legal order, enshrined in Article 2(4) of the United Nations Charter: All states “shall refrain in their international relations from the threat or use of force.” In particular, a state may not violate the territorial integrity of another state. Today, Putin explicitly acknowledges that Russian troops were active in Crimea, and he continues to threaten cross-border military intervention. We have daily reports of violations of Ukrainian airspace, as well as of the Russian troops massed near the border. There are even reports of stealth military operations by Russian forces within Ukraine.

The crisis of international legality in Ukraine began immediately after the closing of the Sochi Olympics on Feb. 23. That day also marked the first large pro-Russian rally in Crimea. Within a week, the Russian parliament granted President Vladimir Putin the power to use military force in Ukraine. By the middle of March, after the deployment of armed men in unmarked uniforms and a hastily called referendum, Russia annexed Crimea. By the first week in April, the pattern of pro-Russian action by armed men in unmarked uniforms seizing government buildings had spread to cities of eastern Ukraine. As violence spread, Putin spoke of a “right” to send in troops to protect “Russians.” Russia maintained some 40,000 troops near the border in order to substantiate that threat. Violence, threats, annexation — none of this can be reconciled with international law.

We do not yet know the endgame of the forces at play in Ukraine. Matters may spiral out of control, leading to a large Russian invasion. More likely, events will simply continue at a low boil, making impossible any stabilization of the political and economic situation for a long time to come. But even though we can’t know the political future, it is not too early to reflect on the legal significance of the events of the past few months. The international legal order of national security is now a shambles. It will take considerably more than a settlement in Ukraine to put it back together.

A third principle was expressed in the security guarantees of the U.N. system. A state has the legal right to defend itself in response to an armed attack. It also has a right to enlist the help of others as a matter of collective self-defense, until the Security Council acts. Primary responsibility for the maintenance of international peace was assigned to the Security Council. Ukraine has a right of self-defense against forces trying to seize its territory or disrupt its law enforcement efforts, but no one will come to its aid. There is no possibility of Security Council action. We are back to the stalemate of the Cold War. Just as then, there may be no middle ground, as countries fall under the control of one major power or the other. Poor Ukraine, if it imagined itself a sovereign entity protected by international law enforced by the organs of the United Nations.

Alongside the laws that purported to manage recourse to violence, there were the Geneva Conventions, international laws aimed at managing the way in which a state may deploy force, if and when it decides to do so. At the foundation of that body of law is a requirement of public transparency. Military forces must wear uniforms in order to distinguish them from civilians and in order to keep visible an operational chain of command and a chain of legal responsibility. The man with a gun must have an identity if he is to be held accountable and if the state that sent him is to be held legally accountable. In Ukraine, Russian forces have been operating without identification and, for the most part, without acknowledgment.

These four principles — the prohibition of the use of force, the respect for borders, the Security Council responsibility for maintenance of peace and the requirement of public transparency — were the basis for international law among independent states. Those principles have all been cast aside, with little effort even to offer a legal justification. Russian action in Ukraine tells us clearly that international relations based on law instead of violence remain fragile and under threat.

The events in Ukraine, however, should not be viewed in isolation, as if they came from nowhere. Disregard for international law in the post–Cold War era was thoroughly demonstrated in the American invasion of Iraq. The United States used force to accomplish “regime change”; it disregarded the Security Council; it used private contractors and unidentified agents in place of identifiable troops. While it did not formally redraw the borders of Iraq, informally the north of Iraq has operated as an autonomous Kurdish region since the invasion. The United States had no more legal right to invade Iraq than Russia had to seize Crimea.

Of course, American violations of international law in Iraq are no excuse for Russian actions today. America — and Iraq — paid a steep price in blood and treasure for that decision to flout international law. Nevertheless, that past has certainly weakened our ability to claim the high ground of law or even to rally support for Ukraine. To the rest of the world, all of it looks like the misbehavior of nations that still dream of spheres of influence.

Russia did learn one important lesson from the American fiasco in Iraq: Go in light. The Russian use of unidentified assets in Ukraine is the low-tech version of the contemporary American reliance on unidentified drones. This is what future wars will look like: not the massed armor of battalions on the move, but a close intermeshing of targeted violence and information control in pursuit of political ends. International law is not at all prepared for this future. It never even mastered its past.