Russia continues to insist that Syrian forces shot down a majority of the allied cruise missiles launched against the Assad regime by the United States, France and the United Kingdom on April 13, 2018. However, Moscow’s assertions are extremely dubious because low-flying cruise missiles are extremely difficult to intercept, particularly over land. The Pentagon maintains that all of the missiles launched against Syria hit their targets.

Russia claims that only twenty-two of the 105 allied missiles hit their targets. “General Staff of the Armed Forces of the Russian Federation carried out a detailed analysis of the results of the strikes,” Col. Gen. Sergei Rudskoy, Chief of the Main Operational Directorate of the Russian General Staff, told reporters on April 25. “The collected fragments of missiles, study of shell craters, and the nature of destruction of objects allow us to conclude that no more than twenty-two hits of a hundred and five reported ones have been fixed in the target area.”

The Russians further asserted that two of the allied missiles had crashed and were recovered. According to the Russian Ministry of Defense, the crashed missiles are allegedly being examined in Moscow. “Part of the missiles did not reach the targets, apparently because of technical malfunctions, creating a threat of destruction of civilian objects and the death of civilians,” Rudskoy said. “Two of them, including the Tomahawk cruise missile and an air high-precision missile, were transported to Moscow. Now they are being examined by Russian specialists. The results of this work will be used to improve Russian weapons.”

Moreover, the Russians asserted that the allied strike was carried out against facilities where there is no evidence of the presence of chemical weapons. “If, in their opinion, these objects had stocks of poisonous substances, then when striking with cruise missiles large centers of contamination of the terrain could appear,” Rudskoy said. “And in the case of Damascus, tens of thousands of people would inevitably be killed.”

The Pentagon, however, disputes the Russian assertions. The United States carefully evaluated the Syrian sites to make sure that the chance of chemical weapons being released into the atmosphere—and accidentally killing civilians in the vicinity—was minimal. “Was sarin at the three sites that we struck? We believe that it probably was. The careful weaponeering through plume analysis, through the modeling that we do within our targeting enterprise as we look at those targets, we're able to reduce the possibility of that escaping to a very low level,” Lt. Gen. Kenneth F. McKenzie Jr., Director of the Joint Staff, told reporters on April 19. “And we know, empirically, in fact, none did escape, just based on the fact there were no casualties around it.”

Moreover, the United States is convinced that all of the allied cruise missiles made it to their targets. “As we expected, Russia immediately began a misinformation campaign to hide its complicity by sowing doubt and confusion. Following our operations, Russia falsely claimed Syria air defenses shot down a significant number of missiles, when in fact we hit all of our targets,” Pentagon Chief Spokesperson Dana W. White told reporters on April 19. “Of the surface-to-air missiles that the Assad regime launched, nearly every one was launched after the last of our missiles hit their targets. The Russian manufactured air defense systems were totally ineffective. Russia and the regime demonstrated the ineffectiveness of their systems against two days later when those systems engaged accidentally.”

Former U.S. Air Force intelligence chief Lt. Gen. David Deptula—who has run several air campaigns—said that the evidence that the United States hit its targets is self-evident. Even if the Russians and their allies intercepted some of the inbound cruise missiles—or some crashed—it made no difference; the targets were destroyed.

“Debunking Russian fake news and misinformation regarding their claims of interception of Allied cruise missiles in the recent attacks in Syria is easy,” Deptula told the National Interest. “Simply look at the ‘before’ and ‘after’ photos of the intended targets—the answer is there for all to see. The desired effects of the destruction of the intended targets was accomplished, period, dot. Whether or not the Russians intercepted any of the cruise missiles is irrelevant as the targets were destroyed. The degree of precise target destruction indicates that all of the cruise missiles hit their intended targets, but again, the desired effects were accomplished regardless of any Russian attempts to hinder those effects.”

The Russians claim that while the Kremlin’s own advanced S-300V4 and S-400 did not engage—nor were they in a position to do so—that upgraded Syrian weapons shot down most of the allied missiles. “It is to be noted that most high-precision missiles were shot down by S-125, Osa, and Kvadrat Soviet-made air defense systems. These systems were recovered and modernized under the auspices of Russian specialists,” Rudskoy said. “The Syrian Defense Ministry analyzed the results of the missile strike. On its basis, a number of changes have already been introduced into the air defense system of the country, which will further increase its reliability.”

The Russian claims are dubious since it is essentially impossible to provide area air defense coverage against low-flying cruise missiles—only point defense is really feasible. Because the Tomahawk—and other—cruise missiles fly at extremely low altitudes, they are extremely difficult to detect, track and intercept except at very short distances because of the curvature of the Earth and terrain features such a hills, mountains and valleys. A ground-based radar is inherently limited by line-of-sight and against a very low-flying object, the radar horizon is short—as little as twelve miles depending on the terrain features in the area. Even from the air, look-down, shoot-down radars are challenged due the clutter caused by terrain features.

As air defense expert U.S. Air Force Col. Mike ‘Starbaby’ Pietrucha—a former instructor electronic warfare officer in the F-4G Wild Weasel and the F-15E Strike Eagle—explained, cruise missiles pose a nearly insurmountable challenge for air defenses. “So, the Earth is not a smooth marble. Ships have an easier time providing air defense against low-flying cruise missiles, because there are no obstructions between the radar and the target, once the target breaks the radar horizon,” Pietrucha told the National Interest. “Over land, terrain, buildings and foliage all block radar line of sight. The greater the distance to the radar, the harder it is to detect low altitude targets because the chance of blockage by an obstacle, or by sheer Earth curvature, goes up. There are no over-the-horizon fire control radars, obviously.”

Even relatively small changes in altitude from 1,000 feet to down 500 feet result in a reduction of the radar horizon by an additional 25 percent. Descending even slightly to 300 feet further reduces the radar horizon range by an additional 25 percent because of a simple mathematical formula. “The formula for the radar horizon is 1.23 times the square root of the antenna height in feet (answer in nautical miles),” Pietrucha said. “That’s a perfect sphere where the radar loses the ability to see the ground because of the curvature of the earth. Obviously, for a target in the air, the radar detection range is longer because the target may be above the radar horizon.”

One partial solution is to mount the radar on high ground (or rely on airborne cueing if one is very technologically sophisticated). “That’s why you often see radars mounted on hills—to extend the radar horizon. After about 1980, the Soviets started fielding radars on masts, to extend their radar horizon,” Pietrucha said. “They also fielded a radar (NATO: CLAM SHELL) intended specifically to look for cruise missiles at low altitude, and they put that on a mast. For extra bonus, put your masted radars on a hill.”

Even the modernized Syrian air defenses are not up to the task of defeating a cruise missile strike like the one the United States and its allies launched. “The Syrians’ air defense systems are not the same as modern Russian ones,” Pietrucha said. “For older SA-2, SA-3, SA-5 radars, low altitude performance is somewhat limited due to antenna height and older processing techniques.”

Pietrucha dismissed Syrian and Russian propaganda videos of Damascus’ air defenses taking down the American and allied cruise missiles. “So that’s why when I saw Syrian video of an alleged cruise missile shutdown, I immediately doubted it, because the ‘target’ was not very low,” Pietrucha said. “But that’s all besides the point. IF the Syrians shot those missiles down, what caused the large explosions on their military assets? I vote for orbital dolphin lasers.”

As for the two crashed cruise missiles, it is possible that the Russians may have recovered some wreckage. Weapons are not perfect. Missile can and do malfunction, no matter the country of origin. However, the bulk of the Russian claims are mostly extremely dubious.

Why Moscow would make such claims that is not clear. “Short answer: I don't know,” Olga Oliker, senior adviser and director of the Russia and Eurasia Program at CSIS, told the National Interest. “Speculative answer: perhaps because they talked a lot of talk prior to the strike, and this makes it look like the Syrians did something, so Moscow didn't have to. Perhaps because the Syrians operate Russian weapons, and they don't want the weapons to look bad to other buyers. Perhaps because it's fun to troll the Americans and raise doubts about anything that Washington says, particularly once the threat of escalation has passed.”

Dave Majumdar is the defense editor for the National Interest. You can follow him on Twitter: @davemajumdar.

Image: Battle damage assessment image of Shayrat Airfield, Syria, is seen in this DigitalGlobe satellite image, released by the Pentagon following U.S. Tomahawk Land Attack Missile strikes from Arleigh Burke-class guided-missile destroyers, the USS Ross and USS Porter on April 7, 2017. DigitalGlobe/Courtesy U.S. Department of Defense/Handout via REUTERS