Over half of Ukraine's F-16s grounded as Belgian maintenance lags up to 40 weeks

Why it matters

The maintenance bottleneck cuts the usable F-16 fleet roughly in half just as Russia is scaling up jet-powered drone strikes, which now account for the bulk of Russian drone attacks and are far harder to intercept than older Shahed-type drones. The F-16 is currently Ukraine's most effective counter to those drones, so a smaller available fleet directly degrades Ukrainian air defense at a moment when surface-to-air missile stocks are also described as limited. The episode also exposes a structural dependency: Ukraine's Western-supplied fighter fleet is sustained by a single foreign contractor, and any disruption there ripples straight through to operational readiness.

What happened

The Wall Street Journal reported that more than half of Ukraine's F-16 fleet is currently non-combat-ready because phased technical inspections at Belgian contractor Sabena Aerospace Engineering are taking far longer than the same work in the United States — up to 40 weeks in Belgium versus two to six weeks in the US, according to retired US Navy Rear Admiral Mark Montgomery. The maintenance is performed under a US Department of Defense contract worth up to $235.5 million, which one source dates to January 2026. The WSJ-cited Western source warned that, at current rates of use and repair, Ukraine could exhaust its remaining usable F-16s by the end of the year.

A Ukrainian Air Force spokesperson declined to comment to the WSJ, and Sabena Aerospace Engineering declined to comment, citing operational security and the sensitive nature of its military support work. Retired US Air Force Lt. Gen. David Deptula described the situation as "a failure of readiness that is becoming an air defense crisis."

The maintenance problem comes against a worsening drone threat: Russia launched about 2,000 jet-powered drones against Ukraine in September, up from roughly 350 in June, and Ukrainian interception of these faster drones (up to 600 km/h) stands at about 55%, compared with over 90% for older Shahed-type drones. Ukraine plans to buy tens of thousands of 20mm shells for F-16s, with daily needs estimated at roughly 10,000 rounds, as it negotiates with several European countries and manufacturers for supply.

On September 29, President Volodymyr Zelenskyy announced that Belgium will transfer three F-16 fighters to Ukraine by the end of 2026, with other Western partners potentially providing more.

How Ukrainian sources describe it

All eight supplied sources are Ukrainian outlets covering the WSJ and Bloomberg reporting, and they frame the story primarily as an operational and national-security crisis. Coverage centers on the maintenance bottleneck in Belgium, the risk of losing the F-16 fleet within the year, and the urgency of securing more fighters and 20mm ammunition to counter Russian jet-powered drones. Zelenskyy's September 29 announcement of three Belgian F-16s by the end of 2026 is presented as a concrete response, though one report on the same day described an accelerated transfer of three aircraft by the end of 2025 instead.

How international sources describe it

The international voices in the supplied material are all Western officials quoted via WSJ and Bloomberg rather than in independently published international outlets. Retired US Navy Rear Admiral Mark Montgomery supplied the inspection-time comparison; retired US Air Force Lt. Gen. David Deptula framed the delays as a readiness failure becoming an air defense crisis; and US Air Force Lt. Gen. Linda Hurry cited a $14 billion spare-parts shortfall in the US Air Force, while the US Government Accountability Office warned this spring of growing maintenance delays across US military aircraft. These comments situate Ukraine's problem inside a broader strain on Western military aviation sustainment.

Where reporting differs

Sources disagree on several specific numbers. Most cite up to 40 weeks for a phased inspection in Belgium, but one gives up to nine months for the same claim. Estimates of when Ukraine might run out of usable F-16s vary between the end of 2025, the end of 2026, and a vaguer "by the end of the year." The September 29 Belgian transfer is described in some accounts as three F-16s by the end of 2026 and in at least one as three F-16s on an accelerated schedule by the end of 2025. Ukraine's interception rate of Russian jet-powered drones is given as about 55% in most sources and about 57% in one. Reports of recent Russian jet-drone launch volumes variously cite "about 2,000 this month vs ~350 in June," "about 2,000 in September," and "2,800 in August 2026." Finally, only one source dates the $235.5 million US contract with Sabena Aerospace Engineering, placing it in January 2026.

Background

Ukraine received its first F-16s in the summer of 2024 and additional aircraft from the Netherlands in February 2025. The fighters require a phased technical inspection after every roughly 300 flight hours, covering the engine, avionics, hydraulics, fuel lines and other systems. On March 6, then-Belgian Prime Minister Bart De Wever said Belgium could provide F-16s to Ukraine as a source of spare parts in 2025, with combat-capable aircraft planned for 2026. The US signed the $235.5 million Sabena contract in January 2026 (per one source) to handle F-16 maintenance, engine servicing and logistics support. Russia's new jet-powered drones, reaching speeds of up to 600 km/h, are now a dominant part of the drone threat, and Ukraine is testing alternative interceptors while planning to purchase tens of thousands of 20mm shells for its F-16s, with daily needs estimated at roughly 10,000 rounds. The WSJ suggested expanding Ukrainian domestic maintenance capacity or using Romanian facilities as possible mitigations.