On 24 September 2026, United Aircraft Corporation announced on its Telegram channel that it had handed a batch of new Su-57 fighters to the Russian Aerospace Forces. It did not say how many.

That omission is the story. Russia has been building its fifth-generation fighter for more than a decade and a half, and after all that time the outside world still cannot say with confidence how many exist. What we have instead is a set of open-source estimates that disagree with each other — not because anyone is lying, but because they are counting different things.

The Ukrainian outlet Militarnyi puts this batch at two aircraft, which would be the second delivery of 2026 after a pair handed over in February. UAC itself offered no figure at all.

What UAC Actually Said

The corporate statement, carried by the Russian state agency TASS, is short and procedural.

UAC’s chief executive was less procedural and more promotional.

Read the second sentence again. A manufacturer that felt entirely relaxed about its production schedule would not lead with a pledge to fulfil the state order unconditionally. Russian defence-industrial statements tend to advertise the thing that is under pressure.

Three Numbers, All Published in the Same Week

Here is where the counting gets interesting. Militarnyi has identified sixteen Su-57s in service by tail number, and arrives at roughly twenty delivered in total once the February and September batches are added. Zona Militar puts the operational fleet at fewer than twenty. Defence Blog reports that more than forty-four airframes have been built as of 2026 — a figure that includes prototypes and test aircraft, which never reach a squadron.

None of these are official. Moscow does not publish fleet totals for the Su-57, and UAC does not publish batch sizes, so every figure in circulation is reconstructed from photographs, tail numbers and announcements that carefully avoid arithmetic.

The Year With No Deliveries

The gap that matters is 2025, when no Su-57 deliveries were publicly announced at all. Production resumed with the February 2026 batch and has now produced a second.

Both Zona Militar and Militarnyi attribute part of the slowdown to a fire in April 2026 at the Komsomolsk-on-Amur plant, which reportedly damaged a polymer-matrix composite workshop responsible for something in the order of three hundred component types used on the Su-57. A composites shop is not a building you replace in a quarter.

What Is New on These Aircraft

UAC says the delivered fighters differ from earlier production aircraft and reflect what Russia has learned in combat. Beyond that the description thins out quickly. Reporting on the batch points to a rearranged electro-optical sensor fit, including behind the lower rear cockpit, and to compatibility with new air-to-air weapons. The February batch was reported to have introduced a new head-up display, revised formation lights and additional infrared sensors.

What none of the statements provide is a modification list, a serial-number range, or a date by which the Aerospace Forces expect to operate a given number of aircraft.

Two Aircraft Is Still Two Aircraft

It is easy to be glib about this. A fifth-generation programme still delivering fighters in pairs, years after the first serial aircraft reached the Aerospace Forces, is not a programme that is going to mass-produce its way to parity with anyone.

But two aircraft is still two aircraft, and the line at Komsomolsk-on-Amur is running after a year in which it visibly was not. For an industry operating under sanctions, through a war, and around a burned-out composites shop, restarting deliveries is the achievement being advertised here. The number is left out because the number is not the good news.

Sources: TASS; United Aircraft Corporation statements of 24 September 2026; Militarnyi; Zona Militar; Defence Blog.