Since Russia attacked in February, military aircraft, missiles, and drones have filled Ukraine's skies.
Russia and Ukraine have both turned to older anti-aircraft guns to bolster their air defenses.
Those older AA guns have found new life in the effort to shoot down slow, low-flying drones.
Flak is back.
Russian and Ukrainian forces are both discovering that they need lots of air defenses — including relatively low-tech anti-aircraft guns — to deal with the jets, helicopters, drones, and missiles crowding the skies over Ukraine.
Anti-aircraft artillery has been around since World War I, when machine guns and cannons were used to shoot down newfangled flying machines. During World War II, half of the Allied bombers shot down over Germany may have victims of "flak" — a shortened version of a German word for 1930s-era anti-aircraft guns.
By the 1950s, however, the advent of fast, high-altitude jets made cannons and machine guns less useful than guided missiles, which can fly at Mach 4 and reach altitudes of 100,000 feet.
But Russia is now pounding Ukrainian cities and power plants with waves of drones and cruise missiles, and Ukraine is sending its drones to stalk Russian tanks and artillery.
Using big, expensive long-range surface-to-air missiles, known as SAMs, to stop a low-tech drone such as a quadcopter is like using an elephant gun to stop a flea. The increasing reliance on relatively slow, low-flying missiles and aircraft has made flak indispensable again.
"Anti-aircraft guns have been underemphasized, but they should never have been neglected," Nick Reynolds, a land-warfare expert for the Royal United Services Institute, a British think tank, told Insider.
The study urges Western countries to send Ukraine more self-propelled anti-aircraft guns, like the German-made Gepard, and more short-range man-portable air-defense systems, like US-made Stinger missiles.
"In general, gun systems are preferred over missiles where possible due to the much lower cost per engagement and higher availability of ammunition compared with SAMs and MANPADS," the RUSI report says.
Russia and Ukraine are both using Soviet-made S-60 anti-aircraft guns that date to the 1940s. But even more recent Soviet-designed flak, such as the Cold War-era ZSU-23-4 Shilka and 2S6 Tunguska used by both sides, is of limited use against drones.
"Due to its relatively small size, shape, low altitude flight and low speed, legacy Soviet and Russian self-propelled anti-aircraft guns (SPAAGs) such as Shilka and Tunguska also struggle to reliably shoot down the Shahed-136," the RUSI report says.
The study does rate Germany's Gepard — a SPAAG with twin 35-mm cannon first deployed in the 1970s — as "highly effective."
Berlin has pledged 50 Gepards — some of which have already been delivered — as part of a polyglot array of Western air-defense missiles and cannon being sent to Ukraine. Some pundits have also urged the US to send the 1960s-era M163, a 20-mm Vulcan cannon mounted on a M113 armored personnel carrier, though it lacks an onboard radar needed to detect targets.
Old weapons, new dilemmas
The RUSI study suggests that Ukraine faces an air-defense dilemma.
Western-made SAMs are effective against Russian jets and cruise missiles, but Ukraine hasn't received enough spare anti-aircraft missiles to sustain its current rate of fire. MANPADS are good at downing "kamikaze drones" and even cruise missiles, but their short range — coupled with Ukraine's 1,000-mile frontline — means that vast numbers would be needed to protect troops at the front and infrastructure in the rear. Anti-aircraft guns are economical against drones, but their range is short.
In the end, the report says, the Shahed-136 "is simple and not especially difficult to intercept, but most of the current means of doing so are too expensive or draw on unacceptable numbers of weapons required for other defense tasks to provide an adequate medium-term solution."
Older anti-aircraft guns also offer a political advantage. Countries supporting Ukraine have been reluctant to supply some high-tech weapons, including jet fighters and long-range missiles that could strike deep inside Russia, for fear of antagonizing Moscow.
But old-fashioned flak is a safe choice, the RUSI report argues: "Neither MANPADS or SPAAGs should be considered politically sensitive as they are fundamentally defensive weapons needed to protect civilian infrastructure that do not require the absolute latest in cutting-edge technology to be effective."
Even as more sophisticated anti-aircraft weapons have been deployed, anti-aircraft guns have remained useful, albeit in more limited roles. They proved deadly over North Vietnam and in the Middle East — during the October War in 1973, Israeli pilots who dived low to evade SAMs operated by Arab forces often got chewed up by the Shilka and other anti-aircraft cannon.
Operating in conjunction with newer air defenses, anti-aircraft guns can still be lethal against helicopters, attack jets, and drones operating at lower altitudes, as many Russian aircraft are forced to do over Ukraine.
"Medium- and long-rang SAMs are most effective when they are complemented by a robust network of AA guns that can threaten any aircraft trying to avoid higher-altitude threats by flying low," Reynolds told Insider. "Creating such dilemmas through layers of different systems is an essential part of an integrated air defense net."
Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds a master's in political science. Follow him on Twitter and LinkedIn.
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