September 3, 2013, was in many respects an ordinary day for operators of the Russian early-warning radar in Armavir. The radar, the most recent addition to the network of new early-warning stations that Russia has been busily building in recent years, was tracking satellites and cataloging other space objects.

In other respects, though, September 3 was far from ordinary. At 10:16 in the morning Moscow time, the Armavir radar detected two “ballistic objects” that originated in the Mediterranean Sea, roughly 100 kilometers (62 miles) north of Benghazi in Libya. The objects—apparently a missile body and a warhead that separated from it—were following a trajectory toward the Eastern shore of the Mediterranean.

The detection of these two “ballistic objects” would normally go unnoticed by anyone but the Armavir radar station operators. However, it happened during a tense pause in the buildup to a possible US military strike against Syria, which followed accusations of chemical weapons use by Syrian government forces. Although US plans to attack had been put on hold while President Barack Obama asked Congress to approve the use of force, a missile of unknown origin flying toward Syria was an unnerving development.

Russia, which publicly and quite vocally opposed a potential US military strike against the Syrian government, went to great lengths to use the missile launch to emphasize the dangers of military activity in the area (as well as to demonstrate the capability of its early-warning system). The Russian military let it be publicly known that the missile was detected and that the Russian president was informed about the launch. For a few hours the identity of the missile remained a mystery, but then Israel admitted that the launch was part of a test of its Arrow anti-missile defense system. The missile, known as Silver Sparrow and designed to simulate a prospective Iranian ballistic missile, was launched from an aircraft toward Israel so that the Arrow’s radar could detect and track it.

From what is known about the incident, the Russian military quickly learned that the missile didn’t present a threat to anyone. The test was planned long in advance and Israel duly submitted the necessary notifications to air traffic controllers about the upcoming activity. Although Israel is under no obligation to provide direct notification of its ballistic missile launches to Russia or anyone else, the Russian military most likely knew about the planned test. Still, the fact that the identity of the missile was unknown for several hours, and that Russia claimed to see the test as dangerous, shows that in the real world, events can interact in totally unexpected ways. They may trigger a response that nobody can expect, let alone predict.

This is a pattern that has been seen before, in situations as different as the Cuban Missile Crisis in 1962, which saw a number of very dangerous miscalculations and miscommunications; the Norwegian rocket launch in 1995, in which a sounding rocket briefly sent an alarm through the Russian nuclear command and control system; and on September 11, 2001, when it turned out that an ordinary day could be full of unexpected dangers.

It should really come as no surprise that the September 3 incident confirmed the pattern. Indeed, there was no way for the Israeli missile defense program planners to know that their long-planned test would coincide with some particularly tense days in the region. Also, as it turned out, it was the first test involving the Silver Sparrow missile—unlike its shorter-range predecessors, this missile was flying high enough to be detected by the Russian early-warning radar. It is worth noting that the 1995 Norwegian incident also involved a rocket that had never been flown before. And although the Russian military apparently identified the missile correctly this time (as it did in 1995), the fact that the Command Center of the General Staff went on high alert is not something to be taken lightly—this is the center that controls Russia’s nuclear forces.

A discussion of the dangers intrinsic to a complex and tightly coupled system, such as a military operating in combat mode, is not a purely academic exercise. As part of its Conventional Prompt Global Strike (CPGS) program, the United States is working on a number of weapon systems that could conceivably be used in regional crises to deliver limited strikes against high-value targets, such as senior political leaders or key elements of the military infrastructure. Unlike cruise missiles, which are the current weapon of choice for attacks of this kind, some of the CPGS systems under consideration—like intercontinental boost-glide missiles—would look very similar to long-range ballistic missiles for part of their flight. This could create a number of problems that the current US program has failed to address.

One of the questions that this program has left unanswered surrounds the potential consequences of using long-range sea-launched or land-based ballistic missiles to deliver a strike in a real-world crisis. Advocates of the program argue that the risk of miscalculation is small and suggest that if the CPGS launchers fly along a different trajectory or originate from a certain known location, they will not be mistaken for their “regular” counterparts that carry nuclear warheads.

This argument, however, assumes that the circumstances under which these weapons were used would be well understood, and that everybody involved would be making perfectly rational decisions based on the information at hand. But the recent incident shows that these are faulty assumptions—things are much less predictable than we may think they are, and decisions are rarely based on rational calculations. In a rational world it is unlikely, say, that Moscow would mistake a missile launched from somewhere in the ocean for an attack on Russia and launch its nuclear missiles in response. However, in the real world, the use of a ballistic missile in a crisis—an unannounced and unexpected event of the kind no one has dealt with before—could trigger a chain of reactions that may not be under anyone’s control. The risk may be small, but it is not negligible. The incident in the Mediterranean reminded us again that one can never foresee everything.