Although the 21st-century arms race between major powers is focused on stealth technology, fifth and sixth-generation fighter jets that capture the headlines, many smaller powers still rely on legacy aircraft to accomplish more limited mission scopes. Aside from the obvious advantage of lower upfront cost, older platforms also require far less maintenance than the most cutting-edge fighters, which significantly reduces operating costs per flight hour.

Stealth fighters are very intensive to sustain, with Aviation Today noting that the Lockheed Martin F-35 Lightning II requires up to eight maintenance hours per flight hour, for example. As the current fifth-generation Fighter of choice, the F-35 Joint Strike Fighter is a good metric for comparison. The fourth-generation Lockheed Martin F-16 Fighting Falcon, originally made by General Dynamics, has become one of the most popular second-hand fighter jets in recent years.

Depending on the variant and its age, WION News reports that the F-16 costs around half what the F-35 does to fly. The Viper, as it is also called, is still in production, but older airframes are being liquidated as Air Forces modernize. The F-16 and other fourth-generation Fighters require far less maintenance, and when it does, the cost is much lower.

This is a major operational advantage for military forces that operate in permissive environments, with little or no threats to aircraft. Similarly, smaller air forces that perform routine air patrols and supporting missions that do not require stealth can also sustain higher force readiness and accomplish their mission without the added cost of a newer and more ‘exquisite’ airframe.

The Soviet Discount: The Eastern Bloc Used Fighter Market

Credit: Department of Defense

The F-16 is the most mass-produced fighter plane still in production and serves as an excellent example of commonly used warbird options in 2026. Over 4,600 examples have been delivered to more than 25 countries worldwide, and Lockheed Martin still has a backlog of more than 100 jets, but it is far from the only option on the used fighter market. The sanctions imposed in response to the 2022 invasion of Ukraine have been hurting Russian aerospace for the last four years, but thousands of surplus Soviet-built fighter jets are still for sale.

Many fourth-generation platforms have been abandoned since the fall of the Soviet Union, and these aircraft are highly sought after on the used market. Soviet planes like the Mikoyan Gurevich MiG-25 Frogfoot, MiG-29 Fulcrum, and Sukhoi Su-27 Flanker may have closed their assembly lines, but they still have active careers with numerous forces worldwide. That is largely because older Soviet jets can be bought for a minuscule fraction of their original price.

Business Insider reported an excellent case in 2024 that the US purchased 81 Soviet-era aircraft from Kazakhstan, including MiG-29s and MiG-31s. The average price of each was said to be just $19,300 per plane. Although it is unclear why the United States purchased these jets, many countries modernize similar airframes by hiring third-party contractors to modernize them. Installing Western-style avionics, radars, and weapon systems can make a 4.5-generation fighter without the multibillion-dollar cost of a new fleet.

Small Force Strategies in the 21st Century

Credit: US Air Force

Legacy Soviet jets are often sold through third parties or as surplus, unlike newly made 4.5-generation fighters like the Eurofighter Typhoon, Boeing F-15EX Eagle II, or Dassault Rafale, which come with heavy political vetting and usage restrictions. Since these planes are readily available and simpler to acquire, these jets also allow nations with limited diplomatic ties to major powers to maintain a capable air force.

Smaller air forces often opt for these legacy jets because they are good enough for local border security and counter-insurgency operations where advanced stealth is unnecessary. Smaller forces looking to modernize also already have the hangars, ground crews, and pilot training programs derived from 3rd-Gen Soviet fleets that can be quickly adapted for these airframes. A simple transition makes a new used MiG-29 a seamless addition compared to the total overhaul required for a Western jet.

A good example is Ukraine, which has aggressively sought second-hand MiG-29s and Su-27s during the conflict with Russia over the past four years. Ukraine’s defenders have reached out to former Warsaw Pact nations, like Poland and Slovakia, with offers for their surplus jets because their pilots can fly them with zero additional training. Similarly, many forces in Africa and South America have followed the same procurement strategy to replace planes that have been pushed to their limit with similar airframes that do not require additional investment.

The Right Capability at the Right Cost

Credit: US Air Force

Ultimately, a fifth-generation fighter jet like the F-35, Lockheed Martin F-22 Raptor, or even Sukhoi Su-57 Felon offers a massive tactical advantage, but its enormous cost and sustainment are a strategic hurdle that separates great powers from smaller forces. This divide is an intentional barrier to entry that also serves as a security function for the nations that operate stealth aircraft. By controlling access to the technology and the ability to sustain it, countries like the US and Russia have political and military leverage.

For some air forces, there simply is no added value in sinking an enormous amount of resources into building an exquisite fleet of cutting-edge fighter jets. Nations rely on second-hand platforms for missions where stealth is either unnecessary or less critical than raw power and persistence.

In irregular warfare against insurgents or pirates, the high-tech stealth and sensor fusion of a fifth-generation jet are largely wasted; reliable, low-cost ground support is preferred. When it comes to air defense, defending national sovereignty can be achieved with the rapid interception of unauthorized aircraft, which also does not require stealth.

Once again, looking to Ukraine, even in a conflict with a greater power that does have access to fifth-generation jets, the fleet of fourth-generation fighters is still effective in combat by using standoff armaments, which is possible thanks to their higher payload. Unlike fifth-generation jets that must hide weapons internally to remain stealthy, fourth-generation missile trucks can carry massive external payloads. The best example is the USAF’s F-15EX, which carries up to 28,000 lbs of ordnance, exceeding what the F-35 and F-22 can carry in a combat configuration.

No Room for Hangar Queens

Credit: Department of Defense

Transitioning to fifth-generation fleets requires a fundamental overhaul of airbase infrastructure, while older legacy aircraft like the F-15, F-16, and Soviet airframes offer a rugged simplicity that allows them to thrive in austere conditions. Modern fifth-generation fighters use radar-absorbent material coatings that are sensitive to humidity and temperature. Maintenance often requires specialized, climate-controlled facilities to ensure the chemical bonds of these coatings cure correctly.

Maintaining a fifth-generation fleet requires a massive leap in technical skill. The F-35, for example, is estimated to require roughly 160% more maintenance labor hours per flight hour than the F-16 due to the complexity of its integrated systems and stealth surfaces. Fifth-generation aircraft generate terabytes of data. Bases must have secure, high-bandwidth server rooms and clean room avionics labs to process this information and update the aircraft’s mission software.

Aircraft like the F-15EX, Rafale, or Gripen E are often called 4.5-generation because they put a fifth-generation brain inside fourth-generation bodies. These jets do not require climate-controlled hangars for stealth coatings, as they rely on electronic warfare rather than physical shape for survival. Used aircraft like later-model F-4 Phantoms, F-16s, and Soviet MiG-29s or Su-27s are equally prized by nations facing active bombardment or limited budgets due to their ruggedized design heritage.

The US Collection: Former Adversaries Turned Test Dummies

Credit: Department of Defense

Following the fall of the USSR, the US began exploring new ways to acquire the fighter jets built by its once fearsome rival. It has continued to be one of the largest buyers of these legacy airframes to fill out its fleet of aggressor aircraft and testing platforms. Another reason why is to stock an inventory of spare parts to support its allies that fly these same jets despite their new allegiance. The National Interest covered an interesting US-based, privately contracted aggressor training operation, AIR USA. The third-party dog-fighting service provider said:

“The Air USA MiG-29 fleet was imported directly from a former Soviet Union nation. All aircraft are equipped with authentic former Soviet Union manufactured parts. Air USA MiG-29 aircraft are capable of performing any air-to-air mission providing excellent training and flight test opportunities.”

The company has managed to acquire three two-seat trainer versions of the MiG-29UB Fulcrum, and they aren’t the only outfit. Draken International has a mixed fleet with a range of planes built by different manufacturers, including the MiG-21 Fishbed. At least one Su-27 has been spotted in a dogfight over Nellis Air Force Base against a US Air Force F-16 believed to be flown by the third-party operator Pride Aircraft.