Soviet air defence in the late 1950s was built around ground-controlled interception: radar stations tracked an intruder and vectored a fighter onto it by radio. That system worked over populated western regions but broke down across the Arctic and Siberia, where radar coverage was sparse and airfields were hundreds of kilometres apart. A bomber crossing the pole toward Soviet cities might fly for a long time before any interceptor could reach it.

The Tu-128 was the PVO’s answer to that gap. By making the interceptor very large, Tupolev could give it the fuel for long patrols — commonly cited endurance is on the order of two-and-a-half to three hours — and a radar big enough to search for targets with less dependence on ground stations. A small number of regiments, spread along the northern frontier, could in principle cover an enormous area. It was a solution shaped entirely by Soviet geography, and no Western air force ever built anything quite like it.

Smaller Soviet interceptors of the era leaned heavily on the Vozdukh ground-control system to be steered onto their targets. The Tu-128 was designed to need it less. Its Smerch radar was large and powerful for its day, giving the two-man crew the ability to search a volume of sky and lock a bomber-sized target at a reported few tens of kilometres, then engage with radar-guided R-4R missiles at range or infrared R-4T missiles closer in. In the radar-poor north that semi-autonomous capability mattered: a Tu-128 could be pointed roughly toward an intruder and finish the interception on its own sensors, rather than being flown onto the target metre by metre from the ground. Accounts still describe the type as working within the wider ground-control network in normal operations; the onboard radar reduced, rather than eliminated, its dependence on it.

The claim that the Tu-128 is the largest and heaviest interceptor ever operated is widely repeated, and the numbers support it: a length of about 30 metres and a maximum weight in the region of 43 tonnes put it beyond any Western fighter and beyond most contemporary bombers. The reason lies in its origin. Rather than design a clean-sheet fighter, Tupolev adapted the airframe philosophy of its cancelled Tu-98 supersonic bomber, trading agility for the fuel volume and radar size that the Arctic-defence mission demanded. The oversized result was a deliberate engineering choice: only something that large could carry enough fuel, a powerful enough radar and heavy enough missiles to police the emptiest airspace on Earth.

The Tu-128 was a Soviet state product, built for the PVO and never sold on any open market. As a result there is no meaningful flyaway unit price for it in the public record, and no credible cost-per-flight-hour figure exists in open sources. Any precise dollar cost attached to the type should be treated as guesswork rather than a sourced number. What can be said with confidence is that it was a large, fuel-hungry twin-engined aircraft, and that only around 198 were built — a small run reflecting its specialised role rather than any published economics.