What Happened to Ukraine's Ballistic Missile Defense?

Explaining the Reported Drop in Patriot's Effectiveness

Picture: U.S. Army

A few days ago, the Financial Times reported that Ukraine’s ballistic missile defense intercept rates had dropped from around 37 percent in August to just six percent in October, despite a lower number of ballistic missile launches.

This coincides with Russia achieving several significant strikes against Ukraine’s defense industry, including four plants producing drones and drone components, as well as politically sensitive targets such as the EU’s representation in Kyiv and the Cabinet of Ministers building, where Russian ballistic missiles managed to evade Ukrainian defenses.

This post offers some insights into the most plausible explanations for the declining performance of Ukraine’s ballistic missile defenses and explores possible measures to address the problem.

The Russian ballistic missile threat

Two types of Russian conventional ballistic missiles are frequently employed against Ukrainian targets: the ground-launched 9M723 short-range ballistic missile and the air-launched Kh-47M2 Kinzhal medium-range ballistic missile.

The 9M723 entered into service in 2006 and has an official range of 500 kilometers. The Kh-47M2, which is essentially an adapted and slightly modified version of the 9M723 for air-launched use, entered into service in 2017 and has a range of around 1,500 to 2,000 kilometers.

Both ballistic missiles are more accurately described as unitary “aeroballistic” or “quasi-ballistic” systems. While their trajectories resemble a ballistic arc, they are not perfectly ballistic, and both missiles are capable of executing aggressive terminal maneuvers, particularly along the lateral axis of flight (i.e., sideways movement relative to the ground).

These maneuvers are intended to complicate and, ideally, defeat enemy interception. The more unpredictable the flight path, the more kinetic energy interceptors must expend to stay on course, and the harder it becomes to apply predictive guidance. This stresses guidance algorithms, reduces reaction times, and ultimately increases the likelihood of a miss.

The ability of Russian ballistic missiles to perform terminal maneuvers is neither new nor surprising. The American MGM-140 ATACMS, which entered service roughly 15 years before the 9M723, is equally capable of such maneuvers. In addition, Western ballistic missile defense interceptors — including the PAC-2 GEM-T, PAC-3 MSE, and Aster-30B1/0B1NG — were specifically designed with this threat profile in mind.

Nevertheless, according to reporting by the Financial Times, Russia has succeeded in adapting the trajectories of its ballistic missiles in ways that further complicate interception and defeat.

Trajectory adaptations

One reason for the increased success in penetrating Ukraine’s ballistic missile defenses, according to Financial Times reporting, is the use of steeper terminal trajectories than previously observed.

This is at least a somewhat plausible explanation. As noted by me in the FT article, these trajectory adjustments are relatively easy to implement through the onboard computer and mission planning software. In other words, hardware modifications, which are more difficult to execute and risk disrupting established supply chains, are not required.

Just as Western manufacturers continuously mine data from Ukraine to refine their ballistic missile defense algorithms, Russian missile developers likely do the same for their offensive missile systems. They may have observed that missiles launched on steeper terminal trajectories achieved higher penetration rates compared to those on shallower paths and subsequently replicated this success at scale.

Why might steeper trajectories be more successful? One explanation is that a steeper trajectory increases the vertical speed of the incoming missile, shortening the engagement window during the missile’s terminal approach. This reduces the time available for interceptors to detect, acquire, and adjust their vertical momentum, especially if they were previously more optimized for shallower trajectories.

While shallower trajectories should, in principle, allow for greater lateral maneuverability, this advantage may be less relevant against interceptors like the PAC-3 MSE, which are known for their high agility. It is therefore plausible that Russian designers concluded — and saw empirically confirmed — that if lateral maneuvers can be countered, reducing reaction times through steeper trajectories offers a better chance of success, even at the cost of more limited lateral maneuvering.

Alternative explanations for declining intercept rates

Two other plausible explanations stand out for the reduced success rates of Ukraine’s ballistic missile defense.

First, Russia may increasingly use its ballistic missiles outside Patriot or SAMP/T defended areas. In other words, rather than trying to overwhelm Ukraine’s ballistic missile defenses, Russian operators choose to strike where Ukraine is known not to deploy them for lack of available systems.

For example, recent months have seen increased use of ballistic missiles against frontline targets and those in the immediate rear area. Unless Ukraine is actively maneuvering Patriot or comparable systems in these areas for SAMbush attacks (using long-range air defense assets to surprise enemy aircraft near the frontline), its shortage of ballistic missile defense systems forces it to prioritize deployment areas much deeper behind the frontline. In this case, Russian ballistic missiles striking frontline targets will remain naturally undefended.

Similarly, Ukraine is known to protect only a few major cities and critical infrastructure sites, while many others remain undefended. This is one reason why Ukraine has stated a nominal requirement of at least ten additional Patriot fire units to establish minimal nationwide coverage (in addition to the seven to eight it already deploys).

To produce a clearer assessment of ballistic missile defense performance, Ukraine would need to release data not only on how many ballistic missiles Russia launched and how many were intercepted, but also on how many intercept attempts were made. This data, however, is not provided, which is one reason why the quantitative figures have limited utility without additional context and qualitative insights to support them.

Second, due to Ukraine’s severe interceptor shortage, Ukraine is likely to allocate only one interceptor per incoming ballistic missile in engagements. In contrast, when Ukraine first received Patriot, the AFU often launched two or even three interceptors per target, as shown in at least one video that surfaced on social media.

Regardless of the individual interceptor’s success rate, launching multiple interceptors significantly increases the overall probability of intercept. When Ukraine is limited to one interceptor per target, the likelihood of successful interception naturally declines.

Admittedly, this may not explain the recent drop, as interceptor shortages have persisted for months and were already a factor in August, when intercept rates were reportedly higher. Still, it remains an important consideration when assessing the current and future effectiveness of Ukraine’s ballistic missile defense going forward.

Ultimately, the declining intercept rates are likely the result of a confluence of factors, only some of which are observable from the outside and without access to classified sources.

Lessons and implications for Ukraine and Europe

This episode illustrates the ongoing cycle of adaptation and counter-adaptation that remains central to warfare, including in the conventional missile domain. Just as Russia has likely used intercept data to enhance the penetrability of its missile systems, Western manufacturers are almost certainly analyzing the same data right now in an attempt to negate the temporary Russian advantage and raise intercept rates once again.

That said, there are clear limits to what missile defense — particularly against ballistic missiles — can achieve. Even if Lockheed Martin and Raytheon succeed in restoring PAC-3 MSE’s single-shot intercept rate to around 60 to 70 percent against Russian ballistic missiles, where it reportedly stood before the recent drop, the offense-defense cost balance remains inherently skewed against the defender.

Ukraine’s offensive missile capabilities must therefore be accelerated in parallel with efforts to strengthen its missile defense. Enabling Ukraine to target the ballistic missile supply chain and production facilities inside Russia, where feasible, should be a priority.

This is also a critical lesson for European states as they prepare for war with Russia. A point of diminishing returns has arguably been reached, where further European investments in an imperfect missile defense architecture offer only marginal gains at great cost. Instead, European states must finally commit to large-scale production and acquisition of conventional counter-strike capabilities that can deny Russian advances and credibly threaten retaliation.